Air cleaning device

Abstract

To provide an air cleaning device that is compact and can save consumption power, and can obtain sufficient cleaning effect.SOLUTION: The fine particles of a photocatalyst 502 are attached to a surface of a nonwoven fabric 501 having a predetermined thickness and having permeability and translucency and the fibers 504 constituting the inside of the nonwoven fabric, and a three-dimensional space in which the fine particles of the photocatalyst are scattered in three dimensions is provided inside the nonwoven fabric. The light incident from a light source disposed outside the nonwoven fabric 501 reaches the fine particle surface of the photocatalyst in the three-dimensional space and is diffusely reflected, and each fine particle in the three-dimensional space mutually receives the diffusely reflected light. An air flow to be purified is formed in a direction along a substrate surface of the substrate supporting the nonwoven fabric 501, and it is pushed into the three-dimensional space of the nonwoven fabric.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to an air cleaning device. [Background technology]

[0002] Air purifying devices that remove odors, dust, bacteria, viruses, etc. from the air are used in various fields such as commercial and home use. Air purifying devices include devices that use ozone, plasma, ultraviolet rays, or photocatalysts. Air purifying devices that use photocatalysts are superior to other devices in terms of noise, size, and cost.

[0003] When light is irradiated onto a photocatalyst, such as titanium dioxide or tungsten oxide, it reacts with water and oxygen in the air to generate active oxygen, which has a strong oxidizing effect and exerts effects such as deodorization and sterilization. For example, Patent Document 1 discloses an air purifying device that uses a photocatalyst.

[0004] The air purifying device disclosed in Patent Document 1 includes a light source that activates a photocatalyst, a deodorizing filter containing a photocatalyst that is arranged around the light source, and a fan that sends air to the deodorizing filter. The fan is operated to send air into the deodorizing filter, and the air is purified by the photocatalyst in the deodorizing filter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-094678 A [Patent Document 2] JP 2009-078058 A [Patent Document 3] JP 2003-103142 A [Patent Document 4] JP 2008-055161 A [Patent Document 5] JP 2019-017855 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the air purifying device disclosed in the patent document, the air comes into contact with the photocatalyst only when passing through the deodorizing filter, so the contact time is short and the cleaning effect is insufficient. Also, the fan needs to have enough wind power to pass the air through the deodorizing filter, which causes the fan to become large and consumes a lot of power.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an air purifying device that is compact, saves power consumption, and provides sufficient cleaning effect. Another aim of the present invention is to provide an air purifying device that can be used in a wide variety of places while maintaining its high cleaning performance. [Means for solving the problem]

[0008] The following configurations are each a means for solving the above problems.

[0009] <Configuration 1> A three-dimensional space in which the photocatalyst particles are three-dimensionally dispersed within the nonwoven fabric of the device is provided by attaching photocatalyst particles to the surface of the nonwoven fabric having a predetermined thickness and having air permeability and light transmissivity and to the fibers constituting the interior of the nonwoven fabric, Light incident on the nonwoven fabric from a light source disposed outside the fabric reaches the surfaces of the photocatalyst particles in the three-dimensional space and is diffusely reflected, and each particle in the three-dimensional space receives the diffusely reflected light from the other particles, forming an air flow to be purified in a direction along a substrate surface of a substrate supporting the nonwoven fabric; A part or all of this air flow is pushed so as to flow into the three-dimensional space of the nonwoven fabric, A method for purifying said air stream.

[0010] <Configuration 2> 2. The method for purifying an air flow according to claim 1, wherein the effective cross-sectional thickness of the nonwoven fabric is 0.5 mm or more and 2 mm or less.

[0011] <Configuration 3> 3. The method for purifying an air flow according to claim 2, wherein the photocatalyst is fine particles having an average particle size of 100 nm or less.

[0012] <Configuration 4> The method for purifying an air flow according to configuration 2, wherein the photocatalyst is fine particles having an average particle size of 20 nm or more and 50 nm or less.

[0013] <Component 5> A nonwoven fabric for purifying airflow, characterized in that photocatalytic microparticles with an average particle size of 100 nm or less are attached to the fibers that make up the surface and interior of the nonwoven fabric, which has an effective cross-sectional thickness of 0.5 mm or more and 2 mm or less, so that the photocatalytic microparticles are scattered three-dimensionally inside the nonwoven fabric, and the nonwoven fabric has breathability and translucency in all directions in the three-dimensional space.

[0014] <Component 6> 6. The nonwoven fabric for purifying an air stream according to claim 5, wherein the photocatalyst is titanium dioxide doped with metal ions.

[0015] <Component 7> 6. The nonwoven fabric for purifying an air flow according to claim 5, wherein the photocatalyst portion is coated with hydroxyapatite. Effect of the Invention

[0016] According to the present invention, the device is compact and can save power consumption, and since the air to be purified flows in the three-dimensional space of the nonwoven fabric, a sufficient cleaning effect can be obtained. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing the appearance of an air purifying device according to an embodiment of the present invention. [Diagram 2]FIG. 1 is a diagram showing the structure of an air purifying device. [Diagram 3] FIG. 2 is an external view of the air purification unit, where (a) is a top view and (b) is a cross-sectional view taken along line XX in (a). [Figure 4] FIG. 13 shows a case where air purification units are used in a stacked manner, where (a) is a top view of a first air purification unit and a third air purification unit, and (b) is a top view of a second air purification unit. [Diagram 5] FIG. 13 is a side view showing a case where the air purification units are stacked for use. [Figure 6] FIG. 2 is a diagram showing a main part of the rack. [Figure 7] FIG. 2 is a conceptual diagram of an air purifying device according to a first modified example. [Figure 8] FIG. 8 is an enlarged view of the area enclosed by the dotted line in FIG. 7. [Figure 9] FIG. 11 is a conceptual diagram of an air purifying device according to a second modified example. [Figure 10] FIG. 10 is an enlarged view of the area surrounded by the dotted line in FIG. [Figure 11] FIG. 2 is an explanatory diagram showing the surface structure of a photocatalyst part. [Figure 12] FIG. 2 is a cross-sectional view showing the structure of a nonwoven fabric. [Figure 13] FIG. 2 is a perspective view showing a container and its internal structure. [Figure 14] 1 is a graph showing a performance evaluation of an air purifying device. [Figure 15] FIG. 13 is a perspective view showing a structure in which containers are connected together. [Figure 16] A cross-sectional view of an air conditioner duct and a living room. [Figure 17] FIG. 2 is an explanatory diagram of the cross-sectional structure of the nonwoven fabric of the present invention and a photocatalyst attached to the fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] An air purifying device according to an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the direction in which the air purifying units of the air purifying device are stacked is the up-down direction, the longitudinal direction of the rectangular air purifying unit is the left-right direction, and the direction perpendicular to both the up-down direction and the left-right direction is the front-rear direction. The up-down, left-right, and front-rear directions are directions arbitrarily determined for the purpose of explaining this embodiment. EXAMPLES

[0019] An air purifying device 1 according to this embodiment is formed in a box shape, as shown in the external appearance in Fig. 1, and is a device that takes in air from an inlet 11 and purifies the air by inactivating viruses, bacteria, etc. in the air with an internal photocatalyst. As shown in Fig. 2, the air purifying device 1 includes a main body 10, a blower 20, an air purifying unit 30, a rack 40, a power source 50, and a light source 60.

[0020] The main body 10 is a case member that houses the components of the air purifier 1, and is made of synthetic resin. An air intake port 11 for taking in outside air is formed on the top surface of the main body 10, and an air exhaust port 12 for expelling the air taken into the inside of the main body 10 is formed on the bottom surface. In this embodiment, the air intake port 11 and the air exhaust port 12 are disposed at positions facing each other, and the air taken in through the air intake port 11 flows from above toward the air exhaust port 12 below.

[0021] The blower 20 is disposed near the air intake 11, and sends the air that has entered through the air intake 11 towards the air purification unit 30. The blower 20 includes a fan and a motor that rotates the fan (not shown). For example, a sirocco fan or a propeller fan is used as the fan. For example, an inverter motor that controls the frequency by an inverter circuit is used as the motor. The motor is driven by a power source 50, which will be described later. The rotation speed of the fan can be changed by a user's operation.

[0022] The air purification unit 30 is a unit that uses photocatalysis to remove dust, bacteria, and viruses contained in the air sent by the blower 20. As shown in FIG. 3, the air purification unit 30 includes a frame 31, a photocatalyst section 32, and a ventilation section 33.

[0023] The frame 31 is a rectangular synthetic resin frame, and the inside is divided into a first region 31a and a second region 31b. The first region 31a and the second region 31b are regions obtained by dividing the inside of the frame 31 into left and right regions by a boundary line 31c in the front-rear direction. In Fig. 3(a) and (b), the first region 31a is formed larger than the second region 31b. The sizes of the first region 31a and the second region 31b may be the same, or the second region 31b may be larger than the first region 31a. In addition, a frame material may be disposed on the boundary line 31c and used to fix a nonwoven fabric or a transparent or translucent substrate, which will be described later.

[0024] The photocatalyst section 32 is disposed in the first region 31a of the frame 31. The photocatalyst section 32 contains a photocatalyst, and purifies the air passing over the surface of the first region 31a.

[0025] The photocatalyst section 32 is formed by supporting a photocatalyst on a substrate. In this embodiment, a sheet member made of nonwoven fabric is used as the substrate. The sheet member is attached to the frame portion of the frame 31 so as to cover the first region 31a of the frame 31.

[0026] Metal ions, semiconductors, etc. are used as photocatalysts, and examples of semiconductor photocatalysts include titanium dioxide (TiO2), zinc oxide (ZnO), iron oxide (Fe2O3), tungsten oxide (WO3), gallium phosphide (GaP), gallium arsenide (GaAs), cadmium sulfide (CdS, strontium titanate (SrTiO3)). Titanium dioxide is inexpensive and has excellent chemical stability, and in this embodiment, titanium dioxide (hereinafter referred to as "titanium oxide") is used as an example for explanation.

[0027] The nonwoven fabric used is made from acrylic resin, polyester, polypropylene, or the like. The nonwoven fabric is impregnated with or coated with a liquid mixture of titanium oxide and a binder (adhesive), etc., to support the titanium oxide on the nonwoven fabric. Hereinafter, a sheet member supported with titanium oxide will be referred to as a titanium oxide sheet. By preparing the titanium oxide sheet in advance, it can be cut and used according to the size of the first region 31a of the frame 31 to be used.

[0028] Also, a visible light responsive photocatalyst can be used as the photocatalyst. For example, titanium oxide doped with metal ions is used as the visible light responsive photocatalyst. Titanium oxide has a strong air purification effect when irradiated with ultraviolet light, but its activity to visible light is poor. It is known that doping titanium oxide with metal ions increases its responsiveness to visible light. By using such a visible light responsive photocatalyst, it is possible to purify the air using visible light such as LED. As the metal ions, iron, platinum, chromium, copper ions, etc. are used.

[0029] The photocatalyst section 32 may be coated with hydroxyapatite (Ca10(PO4)6(OH)2). Hydroxyapatite is a basic calcium phosphate. Hydroxyapatite has excellent properties for adsorbing substances, and in particular, it adsorbs bacteria, viruses, ammonia, and other amino acids. However, as its adsorption reaches a saturation state, it must be replaced periodically. On the other hand, titanium oxide, which is a photocatalyst, can decompose bacteria, viruses, and other substances that it comes into contact with due to its strong oxidizing power, but its adsorption power is poor. Therefore, by coating titanium oxide, which is a photocatalyst, with hydroxyapatite, it is possible to adsorb many harmful substances in the air and achieve excellent air purification effects. Instead of hydroxyapatite, titanium apatite (TiCa9(PO4)6(OH)2), which also has excellent adsorption properties, may be used. Titanium apatite is a compound in which titanium is mixed into calcium hydroxyapatite (Ca10(PO4)6(OH)2) and one of the calcium atoms is replaced by titanium.

[0030] The ventilation section 33 passes the air purified by the photocatalyst section 32 and sends it downwards of the air purifying device 1. The ventilation section 33 is disposed in the second region 31b of the frame 31, and the ventilation holes 33a for passing the air are formed in a sheet member formed of nonwoven fabric. The sheet member is attached to the frame portion of the frame 31 so as to cover the second region 31b of the frame 31. The ventilation holes 33a are a plurality of through holes provided in the sheet member, as shown in FIG. 3(a). The ventilation section 33 may be formed as ventilation holes in the entire second region 31b, i.e., the second region 31b itself, instead of forming a plurality of ventilation holes 33a in the sheet member.

[0031] As shown in Fig. 2, the air purifying device 1 includes three identical air purifying units 30. The three air purifying units 30 are stacked vertically at a predetermined interval, and opposing air purifying units 30 are stacked with the positions of the photocatalyst section 32 and the ventilation section 33 reversed. In addition, a light source 60 is disposed between the opposing air purifying units 30. The relative positions of the three air purifying units 30 and the light source 60 will be described later.

[0032] The power supply 50 is connected to the air blower 20 and the light source 60 by a power line, and supplies power to the air blower 20 and the light source 60. A mobile battery such as a lithium battery mounted on a smartphone or the like is used as the power supply 50. The mobile battery is a thin storage battery, and is charged as appropriate according to the power storage state of the air purifying device 1 before use.

[0033] In this embodiment, as described below, it is preferable to use an LED as the light source 60, and the air blower 20 only needs to generate an air flow that flows over the surface of the air purification unit 30, so that power consumption can be reduced. Therefore, a small storage battery such as a mobile battery can be used. By using a storage battery, a plug for obtaining power is not required, the air purification device 1 can be carried around, and the device itself can be made smaller.

[0034] The light source 60 irradiates the air purification unit 30 with light to activate the photocatalyst. The light source 60 can be an ultraviolet lamp, a white light lamp, a fluorescent lamp, an LED (Light Emitting Diode), or the like. When titanium oxide doped with metal ions is used as the photocatalyst, an LED can be used because it has good visible light responsiveness. When an LED is used, it has a long life compared to other light sources and can be used for a long period of time without replacement, and it consumes less power, so costs can be reduced. In addition, the use of a power-saving, long-life LED can contribute to the realization of carbon neutrality.

[0035] When using LEDs as the light source 60, white LEDs may be used. By using white LEDs, a high-intensity light source can be provided at a lower cost than when using UV-LEDs, and a large cooling device is not required. Therefore, the air purifying device 1 can be made smaller.

[0036] The positional relationship of the three air purification units 30 and the positional relationship of the light source 60 will be described in detail with reference to Figs. 4 and 5. The three air purification units are a first air purification unit 301, a second air purification unit 302, and a third air purification unit 303. Each of these air purification units 30 includes a photocatalyst unit 32 and a ventilation unit 33. In the drawings, the ventilation unit 33 does not show a plurality of ventilation holes 33a. The ventilation unit 33 may be a plurality of ventilation holes 33a, or the second region itself may be the ventilation hole. These air purification units 30 are mounted on a rack 40. Hereinafter, the air purification unit 30 will be described by selectively using the first air purification unit 301, the second air purification unit 302, and the third air purification unit 303 according to the contents of the description.

[0037] As shown in Figs. 5 and 6, the rack 40 includes a first side plate 401 and a second side plate 402 arranged opposite to each other. As shown in Fig. 6, holding members 401a and 402a extending in the front-rear direction are attached to the opposing wall surfaces of the first side plate 401 and the second side plate 402. The holding members 401a and 402a include grooves 401aa and 402aa whose cut surfaces in the up-down direction are U-shaped. Each air purifying unit 30 is inserted by sliding its short side into the grooves 401aa and 402aa, and is held between the first side plate 401 and the second side plate 402. Each air purifying unit 30 may be fixed to the grooves 401aa and 402aa by a stopper (not shown), or may be fixed by attaching plate members opposite to each other in the front-rear direction of the rack 40 and sandwiching the air purifying unit 30 from the front-rear direction.

[0038] As shown in FIG. 5, the first air purification unit 301, the second air purification unit 302, and the third air purification unit 303 are stacked in this order with a gap between them in the vertical direction and arranged on the rack 40. The three air purification units 30 are arranged in the opposite directions between the opposing air purification units 30. That is, the first air purification unit 301 and the second air purification unit 302 are arranged so that the photocatalyst part 32 and the ventilation part 33 are reversed, as shown in FIGS. 4 and 5. In the first air purification unit 301, the photocatalyst part 32 is on the right side and the ventilation part 33 is on the left side, but in the second air purification unit 302, the photocatalyst part 32 is on the left side and the ventilation part 33 is on the right side, so that the left and right are reversed. The third air purification unit 303 is arranged in the same direction as the first air purification unit 301.

[0039] By arranging the three air purifying units 30 as described above, the ventilation sections 33 of the first air purifying unit 301 and the second air purifying unit 302 are arranged at positions symmetrical to each other in a top view, as shown in FIG. 6. When air is sent by the blower 20, an airflow is generated between the ventilation section 303 of the first air purifying unit 301 and the ventilation section 33 of the second air purifying unit 302. The ventilation sections 33 of the second air purifying unit 302 and the third air purifying unit 303 are also arranged at positions symmetrical to each other in a top view, and an airflow is generated between the ventilation section 33 of the second air purifying unit 302 and the ventilation section 33 of the third air purifying unit 303. Therefore, the air that enters from the intake port 11 flows while meandering left and right, and is discharged from the exhaust port 12.

[0040] The light sources 60 are disposed between the first air purification unit 301 and the second air purification unit 302, and between the second air purification unit 302 and the third air purification unit 303. The light source 60 between the first air purification unit 301 and the second air purification unit 302 is attached to the second side plate 402 of the rack 40. The light source 60 between the second air purification unit 302 and the third air purification unit 303 is attached to the first side plate 401 of the rack 40. Therefore, the two light sources 60 are disposed symmetrically in top view.

[0041] In this way, the air sucked in from the air inlet 11 flows in a serpentine manner between the opposing air purification units 30, and is purified by sufficient contact with the photocatalyst. In addition, the light sources 60 attached between the air purification units 30 are installed alternately on the first side plate 401 and the second side plate 402, so that the effect of the photocatalyst can be exerted while minimizing the number of light sources 60.

[0042] (Air purification methods) A method for purifying air using air purifier 1 will be described with reference to Figures 2 and 5. A user of air purifier 1 turns on a switch (not shown) of air purifier 1 to start operation. When the switch is turned on, power is supplied from power source 50, a motor (not shown) of blower 30 is driven, the fan is operated, and light source 60 is turned on.

[0043] When the fan is operated, external air flows in through the intake port 11 and is sucked into the air purifying device 1, as shown in Fig. 2. The sucked air flows rightward across the surface 301a of the first air purifying unit 301, and passes through the ventilation section 33, as shown in Fig. 5. As the air flows across the surface 301a of the first air purifying unit 301, the air is purified by the photocatalyst of the photocatalyst section 32.

[0044] The air that has passed through the ventilation section 33 of the first air purification unit 301 flows leftward between the first air purification unit 301 and the second air purification unit 302. At that time, the air comes into contact with the back surface 301b of the first air purification unit 301 and the front surface 302a of the second air purification unit 302, and is purified by the photocatalysts of the photocatalyst sections 32 of the first air purification unit 301 and the second air purification unit 302.

[0045] The air that has flowed between the first air purification unit 301 and the second air purification unit 302 passes through the ventilation section 33 of the second air purification unit 302, and flows rightward between the second air purification unit 302 and the third air purification unit 303. At that time, the air comes into contact with the back surface 302b of the second air purification unit 302 and the front surface 303a of the third air purification unit 303, and is purified by the photocatalyst of the photocatalyst section 32 of the second air purification unit 302 and the third air purification unit 303.

[0046] The air that flows between the second air purification unit 302 and the third purification unit 303 passes through the ventilation section 33 of the third purification unit 303, flows leftward along the back surface 303b of the third air purification unit 303, and is discharged to the outside through the exhaust port 12.

[0047] The rotation speed of the fan of the blower 20 can be changed, so that the rotation speed is increased when it is desired to promote the air flow and increase the purification effect, and the rotation speed is decreased when priority is given to reducing noise from the blower 20.

[0048] (Variation 1) In the embodiment, the air purifying device 1 including three air purifying units 30 has been described, but the air purifying device may include three or more air purifying units 30. The air purifying device of this modification will be described with reference to Figs. 7 and 8.

[0049] The air purifying device 100 includes a main body 10, a blower, a first air purifying unit 301 and a second air purifying unit 302 which are air purifying units, a rack 40, a power source, and a light source 60. The structures of the components of the air purifying device 100 are the same as those of the air purifying device 1. The structures of the respective components have already been described above and will not be described here. Also, the blower and power source are not shown in the drawings.

[0050] In this modification, the ventilation section 33 of the air purification unit 30 is an air hole with the entire second region 31b as an opening, so the ventilation section 33 is omitted in the figure and only the photocatalyst section 32 is shown. The photocatalyst section 32 is a sheet member formed of nonwoven fabric impregnated with or coated with a photocatalyst.

[0051] In this modification, the first air purifying units 301 are attached to the wall surface of the first side plate 401 of the rack 40 at a predetermined interval, and the second air purifying units 302 are attached to the wall surface of the second side plate 402 at a predetermined interval. When the first side plate 401 and the second side plate 402 are viewed from the front-rear direction, the first air purifying units 301 and the second air purifying units 302 are arranged in a comb-like shape. In FIG. 7, three first air purifying units 301 are attached to the first side plate 401, and two second air purifying units 302 are attached to the second side plate 402. The number of air purifying units 30 attached to each side plate may be two or more, or three or more. The first air purifying units 301 and the second air purifying units 302 are arranged so as to face each other and alternate inside the air purifying device 100.

[0052] Unlike the embodiment, the light sources 60 are attached to both the first side plate 401 and the second side plate of the rack 40, between the first air purification unit 301 and the second air purification unit 302. By increasing the number of light sources 60, the activation of the photocatalyst can be improved.

[0053] When the air purifying device 100 is driven, air entering through the suction port 11 moves in a zigzag pattern from side to side between the first air purifying unit 301 and the second air purifying unit 302, which are arranged like the teeth of a comb, and is then blown out from the exhaust port 12. The air moves within the main body 10 while being in sufficient contact with the photocatalysts of the photocatalyst sections 32 of the first air purifying unit 310 and the second air purifying unit 302. Then, viruses 70 in the air that has flowed in through the suction port 11 are inactivated and then discharged from the exhaust port 12.

[0054] More specifically, as shown in Fig. 8, the photocatalyst of the photocatalyst section 32 of the first air purification unit 301 and the second air purification unit 302 absorbs the light emitted from the light source 60. Then, the titanium oxide that absorbs the light is excited, and the electrons and the holes left behind after the electrons are removed generate active oxygen, which inactivates viruses and the like in the air.

[0055] In this modification, the first air purification unit 301 and the second air purification unit 302 are arranged in a comb-like shape to increase the contact area between the photocatalyst and the air, thereby enhancing the purification effect. Also, light sources 60 are attached to both the first side plate 401 and the second side plate 402 between the first air purification unit 301 and the second air purification unit 302, and light from the light sources 60 is irradiated onto the air purification unit 30 from both the left and right sides, thereby promoting the activity of the photocatalyst.

[0056] (Variation 2) In the embodiment and the first modified example, a nonwoven fabric is used as the base material of the air purification unit 30. The base material does not have to be a nonwoven fabric, and a substrate having transparency or translucency can be used. A modified example in which a glass substrate is used as the base material will be described with reference to Figs. 9 and 10.

[0057] Here, transparency refers to the property of an object that allows light to pass through the object and allows the viewer to see through to the other side. Objects with transparency include glass and resins made of polymeric materials, such as PMMA (acrylic), PET (polyethylene terephthalate), and PC (polycarbonate). Translucency refers to the property of an object that the light passing through the object is diffused, making it impossible to clearly recognize the shape of the other side. Objects with translucency include ceramics such as alumina and PLZT (lead lanthanum zirconate titanate).

[0058] The air purifying device 200 includes a main body 10, a blower, a first air purifying unit 301 and a second air purifying unit 302 which are air purifying units, a rack 40, a power source, and a light source 60. The structure of the components of the air purifying device 200 is the same as that of the air purifying device 1, except that a glass substrate is used as the base material of the air purifying unit. The blower and the power source are not shown in the figure.

[0059] The air purification unit 30 has a photocatalyst section 32 and a ventilation section 33, but as in variant example 1, the ventilation section 33 is formed as an opening in the entire second region 31b, so the ventilation section 33 is omitted in the figure and only the photocatalyst section 32 is shown.

[0060] A glass substrate is used as the base material of the air purification unit 30, and the substrate is coated with a photocatalyst. Coating of the substrate with the photocatalyst can be achieved, for example, by spraying a mist or vapor of a modified titanium compound solution onto the glass, or by heating and baking titanium oxide to fix it to the substrate.

[0061] As in the first modification, the air purification units 30 are attached to the wall surface of the first side plate 401, and the second air purification units 302 are attached to the second side plate 402, arranged in a comb-like pattern. In Fig. 9, four first air purification units 301 are attached to the first side plate 401, and three second air purification units 302 are attached to the second side plate 402. Three or more or four or more air purification units 30 may be attached to each side plate.

[0062] The light source 60 is attached to both the first side plate 401 and the second side plate of the rack 40. Unlike the embodiment and the first modified example, the light source 60 is attached not between the first air purification unit 301 and the second air purification unit 302, but at the location of the ventilation section 32 of each of the first air purification unit 301 and the second air purification unit 302. Therefore, the first air purification unit 301 and the second air purification unit 302 can be arranged with a narrower interval. Therefore, more first air purification units 301 and second air purification units 302 can be attached than in the embodiment and the first modified example.

[0063] When the air purifier 200 is driven, the air that enters through the suction port 11 moves between the first air purifier unit 301 and the second air purifier unit 302 arranged in a comb-like shape, meandering from side to side, and is blown out from the air outlet 12. The air moves in the main body 10 while being in sufficient contact with the catalyst coated on the first air purifier unit 310 and the second air purifier unit 302. In addition, since a glass substrate is used as the base material, the light emitted from the light source 60 passes through the glass substrate and reaches from one side of one glass substrate to the other side, as shown in FIG. 10, activating the photocatalyst coated on both sides. In addition, the light that has passed through reaches the second air purifier unit 302 from the first air purifier unit 301, or vice versa, activating the photocatalyst. In this way, the air that enters through the suction port 11 is purified inside the air purifier 200, and the viruses 70 in the air are inactivated and discharged from the exhaust port 12.

[0064] In this modification, the first air purification unit 301 and the second air purification unit are formed in a comb-like shape to enhance the purification effect, and the air purification unit 30 is irradiated with light from the light source 60 from both the left and right sides, thereby promoting the activity of the photocatalyst. In addition, since a transparent or translucent substrate is used as the base material, the light from the light source 60 passes through the substrate to activate the photocatalyst coated on both sides of one air purification unit 30, and also activates the photocatalyst of another air purification unit 30. Furthermore, by arranging the light source 60 in the ventilation section 33 of the air purification unit 30, the number of air purification units 30 that can be installed can be increased.

[0065] According to the air purification unit 30 of this embodiment, the air comes into contact with the photocatalyst while flowing over the surface of the air purification unit 30, so that the air can be in contact with the photocatalyst for a sufficient period of time to activate the photocatalyst. Also, since the air does not need to pass through the photocatalyst section 32 of the air purification unit, a low-output fan may be used, and the air purification device 1 can be made smaller in size.

[0066] According to the air purification unit 30 of this embodiment, air purification is possible using a visible light responsive photocatalyst, which promotes effective use of sunlight and indoor use, and allows the air purification device 1 to be used without being limited in location.

[0067] The air purifying device 1 of the present embodiment is formed by stacking the same air purifying units 30 in the opposite directions. Therefore, the same air purifying units 30 can be mass-produced in the number required for the desired air purifying device 1, thereby improving the manufacturing efficiency.

[0068] According to the air purifying device 1 of the present embodiment, by stacking a plurality of air purifying units 30, the photocatalyst parts 32 on both sides of each air purifying unit 30 come into contact with each other, thereby achieving a high purification effect.

[0069] According to the first and second modified examples, by arranging a plurality of air purifying units in a comb-like shape, it is possible to achieve purification performance several tens to several hundreds of times that of conventional air purifiers.

[0070] In the present embodiment and the first and second modified examples, the sheet member using nonwoven fabric and the glass substrate are described as the base material, but a metal plate, a ceramic plate, or the like may also be used.

[0071] In the present embodiment, blower unit 20 is described as being disposed near air intake port 11, but it may be disposed near air exhaust port 12.

[0072] In this embodiment, an example has been described in which the air purification unit 30 is installed inside the air purification device 1. As shown in Fig. 1, a visible light responsive photocatalyst 80, for example, a photocatalyst in which titanium oxide is doped with metal ions, may be coated on the outer surface of the main body 10 of the air purification device 1. By applying such cousing, it is also possible to sterilize the surface of the air purification device 1 placed indoors.

[0073] In this embodiment, as shown in Fig. 1, a single air purifying device 1 has been used for explanation. Instead of using a single air purifying device 1, different air purifying devices 1 may be stacked and connected vertically for use. By using a plurality of air purifying devices 1 in a connected manner, the purification performance can be improved.

[0074] In this embodiment, as shown in Fig. 11(a), the photocatalyst section 32 has been described on the assumption that the surface is flat. However, as shown in Fig. 11(b), a plurality of protrusions 32a may be formed on the surface of the photocatalyst section 32. By using such a surface structure, the surface area of ​​the photocatalyst section 32 increases, and the amount of harmful substances such as viruses 70 that come into contact with the photocatalyst section 32 increases, thereby enabling a high cleaning effect to be achieved.

[0075] In this embodiment, the frame 30 has been described as having a rectangular shape, but the shape of the frame 30 may be determined in accordance with the shape of the main body 10 of the air purifying device 1, and for example, a circular frame may be used.

[0076] The above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims, not by the embodiment. Various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention. EXAMPLES

[0077] As shown in FIG. 12, the nonwoven fabric 501 of the air purification unit of this embodiment is made of bound fibers of, for example, polyester (PET), polypropylene (PP), polyethylene (PE), etc., which has breathability in both the thickness and width directions.

[0078] This allows the photocatalyst 502 to be dispersed and attached to the surface and inside of the nonwoven fabric 501. The air to be purified passes widely through the inside of the nonwoven fabric 501 as indicated by the arrows 503, and effectively comes into contact with the photocatalyst 502, enhancing the purification effect.

[0079] 13 shows an embodiment of an air purification unit in which the above-mentioned nonwoven fabric 501 is attached to both sides of a transparent plastic substrate 500. The dimensions of the container 600 are 10 cm in length, width and height. The width of the substrate 500 is 10 cm and the length is 7 cm. The substrate 500 is a partition-shaped photocatalyst part of the air purification unit, and the gap of about 3 cm between the substrate 500 and the inner wall of the container 600 is the ventilation part of the air purification unit.

[0080] Two pairs of partition-shaped air purification units as described above are built into this container 600. An air inlet 601 and an outlet 6022 are provided on the top and bottom surfaces of container 600, respectively. Air that enters through inlet 601 passes through the ventilation parts of the two air purification units and is discharged from outlet 602.

[0081] Air flowing in from the ventilation part of the upstream air purification unit passes over the photocatalyst part of the downstream air purification unit along 603, and then flows out from the ventilation part of the downstream air purification unit. In this way, the ventilation parts of each air purification unit are arranged non-linearly from the upstream side to the downstream side, so that the air is in contact with the photocatalyst for a longer period of time.

[0082] LED light sources 604 are placed at various points on the inner wall of container 600 to activate the photocatalytic reaction. Air entering through intake port 601 is purified by coming into wide and long contact with the photocatalyst on both sides of substrate 500. By optimizing the dimensions of container 600 and substrate 500, the thickness of nonwoven fabric 501 to which the photocatalyst is attached, the amount of light from light source 604, and the like, this air purifier can be designed and adjusted to obtain maximum purification capacity using minimum power.

[0083] Figure 14 shows the results of an experiment evaluating the performance of this air purifying unit. A test was conducted to purify air containing 1500 PPM of acetone at a constant flow rate. The vertical axis of this graph shows the concentration of carbon dioxide gas generated when acetone is decomposed by the purifying action. The horizontal axis shows the elapsed time. As purification progresses, the concentration of carbon dioxide gas increases as shown in the figure.

[0084] We compared the purification capacity when the drive power of the light source that irradiates the photocatalyst was set to the standard value (x1), and when it was set to three times (x3) and five times (x5). Both have sufficient purification capacity, but increasing the amount of light used to activate the photocatalyst increases purification capacity. In this example, the required performance is met whether the drive power is (x3) or (x5), so (x3) can be said to be the optimum value for the drive power. The drive power can be adjusted according to the properties and flow rate of the air to be purified.

[0085] Even if such a device is enlarged or the number of light sources is increased, the purification capacity does not necessarily match the cost. Moreover, a lot of prototype development costs are incurred for optimization for each size and shape of the device. In contrast, by connecting multiple containers 600 incorporating the above-mentioned optimally configured purification units, high-performance purification devices of various shapes can be realized.

[0086] For example, multiple air purifying units can be arranged at the air outlet of an air conditioner to purify the exhaust air of the air conditioner. In various manufacturing sites and food factory offices, air containing chemical substances and odors flow into the office through the air conditioner ducts. There is a considerable demand for purifying this air.

[0087] For example, since the exhaust port of an air conditioner is often long horizontally, multiple containers 600 can be connected horizontally for use as shown in Fig. 15. If the side walls of the containers 600 are connected or arranged so that the intake port 601 and exhaust port 602 face in the same direction, the containers can be assembled in any shape. This allows the flow rate of air that can be treated to be increased by the number of containers 600.

[0088] Also, as shown in the figure, for example, the inlet 601 and outlet 602 of two containers 600 can be linked together or arranged in that direction to double the purification capacity. Any number of containers can be linked together. In this case, a connection terminal 605 for supplying power to the light source 604 of each container 600 can be provided on the side wall to electrically connect adjacent containers together and supply power from the outside.

[0089] As shown in Fig. 16, for example, the air outlet 702 of an air conditioner duct 701 in a room 700 has various shapes. By connecting the containers 600 as described above, an air purifying device can be constructed by freely combining them according to the shape of the target location. Moreover, during installation work, the small and lightweight containers 600 can be lined up or stacked one by one in order, making it easy to install them in a narrow duct.

[0090] Furthermore, for example, when performing maintenance, by removing and inspecting just one container, it is possible to estimate the overall level of dirt and deterioration, etc. If it is found that performance has deteriorated, the containers can be removed and replaced one by one, which is overwhelmingly easier to work with than large air purifiers.

[0091] In the above embodiment, the containers 600 are connected by closely contacting their side walls. However, since a larger amount of air can be purified by using several containers 600 inside a duct than by using one container 600, the containers 600 do not necessarily have to be connected without gaps. They may be connected with a small gap by using any connecting frame, adapter, or the like. They may be assembled by fixing each of them to the inner wall of the duct and arranging them in an order to enhance the effect of the purification capacity described above, without directly connecting them. EXAMPLES

[0092] In the present invention, a nonwoven fabric having an effective cross-sectional thickness of 0.5 mm to 2 mm is used. Photocatalyst particles with an average particle size of 100 nm or less are attached to the fibers that make up the surface and interior of the nonwoven fabric. This forms a three-dimensional space inside the nonwoven fabric in which the photocatalyst particles are three-dimensionally scattered. This provides breathability and translucency in all directions in the three-dimensional space.

[0093] Known photocatalysts are applied to the surfaces of various members using a binder. For example, even when a photocatalyst is applied to a sheet as described in the above patent document, the photocatalyst layer is formed only on the surface of the sheet. In the present invention, a three-dimensional space is formed inside the nonwoven fabric in which photocatalyst particles are three-dimensionally scattered, so that when viewed from the cross section of the nonwoven fabric, the photocatalyst particles are present throughout the entire cross section. In the present invention, the thickness as viewed from this cross section is called the "effective cross-sectional thickness."

[0094] FIG. 17(a) is a longitudinal sectional view of a known substrate 510 to which a binder 512 has been applied and then a photocatalyst 514 has been fixed. When viewed from any direction of the cross section, no photocatalyst exists inside. In this case, the effective thickness is zero. On the other hand, FIG. 17(b) is a longitudinal sectional view of a nonwoven fabric 501 of the present invention, and its BB cross section is shown in FIG. 17(c). Thus, when viewed from a cross section in the thickness direction of the nonwoven fabric 501, fine particles of the photocatalyst 502 exist throughout the cross section. In this case, the thickness of the nonwoven fabric 501 is the effective thickness as it is. FIG. 17(d) shows a state in which fine particles of the photocatalyst 502 are attached to the fibers 504 of the nonwoven fabric 501. In this way, the photocatalyst 502 is attached so as to cover the surface of the fibers 504 widely, but the spaces between the fibers 504 are kept as wide as possible. Even if the amount of the photocatalyst 502 attached is smaller, the purification performance is slightly reduced, but sufficient performance is exhibited for practical use.

[0095] From this viewpoint, the effective cross-sectional thickness of all known sheets coated with photocatalyst is zero. If the effective cross-sectional thickness is less than 0.5 mm, the purification ability cannot be fully demonstrated when the air flow to be purified is formed in the direction along the substrate surface of the substrate supporting the nonwoven fabric and flows through the three-dimensional space of the nonwoven fabric. On the other hand, if the thickness is 2 mm or more, it is not easy to provide practical breathability and translucency in all directions of the three-dimensional space. It is preferable that the thickness is such that light reaches the inside of the nonwoven fabric when light is irradiated from a light source to the side of the nonwoven fabric. For this reason, it was decided to use a nonwoven fabric having an effective cross-sectional thickness of 0.5 mm or more and 2 mm or less.

[0096] Furthermore, photocatalyst fine particles with an average particle size of 100 nm or less are attached to the fibers that make up the surface and interior of the nonwoven fabric. If a binder is used to fix a photocatalyst with a large average particle size to the fibers, the binder will fill the spaces between the fibers and impair breathability. It is preferable that the ratio of voids to the cross-sectional area of ​​the nonwoven fabric shown in Figure 17(c) is at least 30% in order to ensure the light transmittance and breathability required in this invention.

[0097] If the nonwoven fabric is impregnated with a binder and the photocatalyst is embedded in it, the photocatalyst will lose its activity. In order to fix the particulate photocatalyst so that it is scattered on the fibers of the nonwoven fabric without using a large amount of binder, it is preferable to use a photocatalyst with an average particle size of 100 nm or less. Furthermore, in order to make the entire inside of the nonwoven fabric glow white when each fine particle in the three-dimensional space receives diffusely reflected light from each other, a photocatalyst with an average particle size of 20 nm or more and 50 nm or less is preferably suitable. In addition, if a photocatalyst coated with hydroxyapatite is used, an extremely small amount of binder is used to fix the nonwoven fabric fibers, and the above-mentioned light transmittance and breathability can be satisfied.

[0098] Particles of this size can be fixed directly to the fibers of the nonwoven fabric. There is no need to impregnate the surrounding area with excess binder, so air circulation and light transmittance can be maintained. If the particles are large, the binder that holds them in place will clog the spaces between the fibers of the nonwoven fabric, reducing air permeability and light transmittance.

[0099] The nonwoven fabric is not intended to act as a filter to remove dust contained in the air to be purified. It is preferable to provide a separate dust filter on the upstream side. This allows the breathability of the nonwoven fabric to be maintained for a long period of time, and it is preferable to pass as much air as possible through the nonwoven fabric to maximize the chemical action of the photocatalyst. The nonwoven fabric is used as a support material to support the photocatalyst by arranging it three-dimensionally.

[0100] In order to improve both breathability and transparency, the lower the density of the nonwoven fabric, the better. However, to ensure ease of handling, a certain level of mechanical strength is required. The fibers of the nonwoven fabric may be either transparent or opaque. In order to create a space in which light diffusely reflected from the surfaces of numerous photocatalyst particles can effectively irradiate the photocatalyst, it is most preferable that the fibers of the nonwoven fabric are made of a white material. This allows the entire interior of the nonwoven fabric to act as a white light source.

[0101] When exposed to light reflected from the surfaces of many photocatalysts in a three-dimensional space, the entire nonwoven fabric becomes a white light source that emits light not only from the surface but also from the inside. This allows the photocatalysts in the nonwoven fabric to demonstrate their maximum capabilities. Furthermore, this effect is further enhanced when light is irradiated from inside the substrate as shown in Figure 10, so that light is shone on both sides of the nonwoven fabric. The light scattering effect can also be increased if the substrate is a reflector that reflects light like a mirror.

[0102] Since the air to be purified passes through the three-dimensional space formed by the nonwoven fabric, it is desirable that all the fine particles in the three-dimensional space inside the nonwoven fabric are activated by forming a state in which they receive diffused light from each other. For this purpose, it is desirable that light is irradiated from both sides of the nonwoven fabric, and it is desirable that the substrate to which the nonwoven fabric is fixed is a transparent body. The substrate itself may be a light emitting body, or light may be incident from a light source on the end face of a transparent plate to give it a function similar to that of a light source.

[0103] One side of the nonwoven fabric is fixed onto, for example, a flat substrate. The air to be purified is then caused to flow parallel to the surface of the substrate. A part or all of the air flow is pushed parallel to the surface of the substrate in the above-mentioned three-dimensional space. In the three-dimensional space formed by the nonwoven fabric, the nonwoven fabric receives diffusely reflected light and is activated to purify the air with photocatalysts, so the air purification capacity is overwhelmingly increased compared to the case of purifying air with a two-dimensionally formed photocatalyst surface.

[0104] Furthermore, when air is pushed through the three-dimensional space formed by the fibers of the nonwoven fabric, turbulence is created. Therefore, the air to be purified does not simply flow in a straight line from one side of the nonwoven fabric to the other, but flows a long distance while generating turbulence, so that it comes into contact with many photocatalysts. This allows for high air purification capabilities.

[0105] According to the present invention as described above, photocatalyst microparticles are arranged in a three-dimensional manner, and light is evenly irradiated onto the photocatalyst by utilizing the interaction of diffuse reflection of light, thereby effectively bringing the air to be purified into contact with these photocatalysts, thereby realizing a device that exhibits high purification capabilities. [Explanation of symbols]

[0106] 1, 100, 200 Air Purifier 10. Main Unit 11 Intake port 12 Outlet 20 Blower section 30 Air Purifier Unit 31 Frame 31a 1st area 31b 2nd area 31c border 32 Photocatalyst section 32a Convex part 33 Ventilation section 33a Ventilation hole 40 racks 50 power supply 60 light source 70 Virus 80 Photocatalyst 301 First air purification unit 302 Second air purification unit 303 3rd Air Purification Unit 301a, 302a, 303a surface 301b, 302b, 303b back side 401 1st side plate 402 2nd side plate 401a, 402a Holding member 401aa, 402aa Groove 500 Base material 501 Nonwoven fabric 502 Photocatalyst 503 Arrow 504 Textiles 510 Base material 512 Binder 514 Photocatalyst 600 containers 601 Intake port 602 Outlet 603 Flow Path 604 Light source 605 Connector 700 Room 701 Duct 702 Vent

Claims

1. A three-dimensional space in which the photocatalyst particles are three-dimensionally dispersed within the nonwoven fabric of the device is provided by attaching photocatalyst particles to the surface of the nonwoven fabric and to the fibers constituting the interior of the nonwoven fabric, the photocatalyst particles being three-dimensionally dispersed within the nonwoven fabric of the device; Light incident on the nonwoven fabric from a light source disposed outside the fabric reaches the surfaces of the photocatalyst particles in the three-dimensional space and is diffusely reflected, and each particle in the three-dimensional space receives the diffusely reflected light from the other particles, forming an air flow to be purified in a direction along a substrate surface of a substrate supporting the nonwoven fabric; A part or all of this air flow is pushed so as to flow into the three-dimensional space of the nonwoven fabric, A method for purifying said air stream.

2. 2. The method of claim 1, wherein the nonwoven fabric has an effective cross-sectional thickness of 0.5 mm to 2 mm.

3. 3. The method of claim 2, wherein the photocatalyst is fine particles having an average particle size of 100 nm or less.

4. 3. The method of claim 2, wherein the photocatalyst is fine particles having an average particle size of 20 nm to 50 nm.

5. A nonwoven fabric for purifying an air flow, characterized in that photocatalytic microparticles having an average particle size of 100 nm or less are attached to the fibers constituting the surface and interior of the nonwoven fabric having an effective cross-sectional thickness of 0.5 mm or more and 2 mm or less, the photocatalytic microparticles are three-dimensionally scattered within the nonwoven fabric, and the nonwoven fabric has breathability and translucency in all directions in the three-dimensional space.

6. 6. The nonwoven fabric for purifying an air stream according to claim 5, wherein the photocatalyst is titanium dioxide doped with metal ions.

7. 6. The nonwoven fabric for purifying an air stream according to claim 5, wherein the photocatalytic portion is coated with hydroxyapatite.

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