Particle attachment device, method for manufacturing filter, and cylindrical honeycomb structure filter

Abstract

A particle attachment device (100) includes a holder (10), a chamber (20), a nozzle (30), an intake port (40), and a flow control member (50). The holder (10) holds a filter substrate (70) having a first end surface (71a) and a second end surface (71b). The chamber (20) communicates with the holder (10) and is configured so that the first end surface (71a) of the filter substrate (70) faces a space in the chamber (20). The nozzle (30) is disposed on an opposite surface (21) of the chamber (20) opposite the first end surface (71a) of the filter substrate (70) and is capable of spraying an aerosol containing particles toward the first end surface (71a) of the filter substrate (70). The intake port (40) is provided on the opposite surface (21) of the chamber (20) and is capable of taking in ambient gas. The flow control member (50) is disposed on the opposite surface (21) on which the intake port (40) is provided and is capable of controlling the flow of the ambient gas.

Description

Technical Field

[0001] This invention relates to a particle attachment device, a method for manufacturing a filter, and a columnar honeycomb structure filter. Background Technology

[0002] Exhaust gases from internal combustion engines such as diesel and gasoline engines contain particulate matter (hereinafter referred to as PM). Soot is harmful to human health, and its emission is restricted. Currently, to address these emissions restrictions, filters represented by DPF and GPF are widely used, which allow exhaust gases to pass through permeable pores to filter PM such as soot.

[0003] As a filter for capturing PM, a columnar honeycomb structure filter with wall flow is known, which has a plurality of first cells extending from a first end face to a second end face and having an opening on the first end face and a sealing portion on the second end face, and a plurality of second cells extending from the first end face to the second end face and having an opening on the second end face and a sealing portion on the first end face, wherein the first cells and the second cells are alternately arranged adjacent to each other with a porous partition wall.

[0004] In recent years, with the strengthening of exhaust gas restrictions, stricter emission standards for PM (PN limit: Particle Matter number limit) have been introduced, requiring filters to have high PM capture performance (high PN capture efficiency). Therefore, it is known to form a layer (hereinafter referred to as "capture layer") on the surface of a porous partition forming a lattice for capturing PM.

[0005] As a device for forming a trapping layer, an apparatus has been proposed, comprising: a workpiece fixing section for fixing a substrate of a honeycomb filter (hereinafter referred to as "honeycomb substrate"); a powder conveying section disposed on one side of the workpiece fixing section, which uses pressurized gas to transport powder (also referred to as "particles") on an airflow (also referred to as "fluid"); an inlet section, which is an unclosed space provided between the powder conveying section and the workpiece fixing section, which further mixes the powder transported from the powder conveying section on the airflow with other gases and introduces it into the honeycomb substrate fixed to the workpiece fixing section; and an attraction section disposed on the other side of the workpiece fixing section, which uses an attraction unit to depressurize the other side of the workpiece fixing section relative to one side of the workpiece fixing section, thereby attracting the gas that has passed through the honeycomb substrate fixed to the workpiece fixing section (Patent Document 1). According to this apparatus, the gas that has passed through the honeycomb substrate is attracted by the attraction unit, thus rectifying the airflow. By introducing powder into the rectified airflow to form a solid-gas two-phase flow, powder can be supplied to the honeycomb substrate uniformly and stably, thus forming a trapping layer of uniform thickness.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5597148 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The device described in Patent Document 1 is primarily suitable for forming a trapping layer on a honeycomb substrate with a small diameter (e.g., less than 140 mm). However, if the trapping layer is formed on a honeycomb substrate with a large diameter (e.g., 180 mm or more), the thickness of the trapping layer tends to become uneven. Specifically, in a cross-section of the honeycomb substrate orthogonal to the flow direction of the fluid, a thick trapping layer tends to form around the central periphery of the honeycomb substrate, while a thin trapping layer tends to form near the outer periphery. This is presumably because, in a cross-section orthogonal to the flow direction of the fluid, particles are supplied to the honeycomb substrate before they have sufficiently diffused to the vicinity of the outer periphery.

[0011] It should be noted that Patent Document 1 is based on the premise of forming a trapping layer on a honeycomb substrate, but for filter substrates other than honeycomb substrates, there is also the same problem that it is difficult to form a trapping layer of uniform thickness depending on its size.

[0012] The present invention was made to solve the problems mentioned above, and its purpose is to provide a particle attachment device and a method for manufacturing a filter that can form a trapping layer of uniform thickness regardless of the type or size of the filter substrate.

[0013] In addition, the present invention aims to provide a columnar honeycomb structure filter with a trapping layer of uniform thickness.

[0014] Solution for solving the problem

[0015] In order to solve the above-mentioned problems, the inventors conducted in-depth research on the structure of the particle attachment device and found that by setting a flow control component that can control the flow of the surrounding gas at a specific position, the fluid in the chamber can generate a swirling flow to promote particle diffusion, thereby completing the present invention.

[0016] That is, the present invention provides a particle attachment device having:

[0017] A retainer for holding a filter substrate having a first end face through which fluid can flow in and a second end face through which the fluid can flow out.

[0018] The chamber communicates with the aforementioned retainer, and the chamber is configured such that the first end face of the aforementioned filter substrate faces the space within the chamber.

[0019] A nozzle, disposed on the opposing surface of the chamber and facing the first end face of the filter substrate, is capable of spraying particle-containing aerosol toward the first end face of the filter substrate.

[0020] An inlet, located on the opposite side of the aforementioned chamber, is capable of drawing in surrounding gas, and

[0021] A flow control component is disposed on the opposing surface where the aforementioned intake port is provided, and is capable of controlling the flow of the surrounding gas.

[0022] In addition, the present invention is a method for manufacturing a filter using the above-described particle attachment device.

[0023] Furthermore, the present invention also provides a columnar honeycomb structure filter, having:

[0024] A columnar honeycomb substrate has a plurality of first cells extending from a first end face to a second end face, wherein the first end face is open and the second end face has a sealing portion, and a plurality of second cells extending from the first end face to the second end face, wherein the second end face is open and the first end face has a sealing portion, wherein the first cells and the second cells are alternately arranged adjacent to each other with porous partitions.

[0025] A trapping layer is formed on the surface of at least one of the first and second pore cells; wherein the difference in thickness of the trapping layer is less than 15 μm.

[0026] Invention Effects

[0027] According to the present invention, a particle attachment device and a method for manufacturing a filter are provided that can form a trapping layer of uniform thickness regardless of the type or size of the filter substrate.

[0028] Furthermore, according to the present invention, a columnar honeycomb structure filter with a trapping layer of uniform thickness can be provided. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a particle attachment device according to an embodiment of the present invention.

[0030] Figure 2 This is a schematic cross-sectional view of the columnar honeycomb substrate used in the particle attachment device according to an embodiment of the present invention.

[0031] Figure 3 yes Figure 2 A schematic end view of a columnar honeycomb substrate.

[0032] Figure 4 This is a schematic top view of a component with multiple blades.

[0033] Figure 5 yes Figure 4 A schematic enlarged cross-sectional view of the component in the circumferential direction.

[0034] Figure 6 This is a schematic diagram of another particle attachment device according to an embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram illustrating a specific example of an aerosol generator.

[0036] Figure 8 A schematic diagram of another particle attachment device according to an embodiment of the present invention.

[0037] Figure 9 This is a schematic cross-sectional view of a columnar honeycomb structure filter according to an embodiment of the present invention.

[0038] Figure 10 yes Figure 9 A schematic end view of a columnar honeycomb structure filter. Detailed Implementation

[0039] The embodiments of the present invention will be described in detail below. The present invention is not limited to the following embodiments. It should be understood that, without departing from the spirit of the present invention, appropriate modifications and improvements made to the following embodiments based on the common knowledge of those skilled in the art are also included within the scope of the present invention.

[0040] (1) Particle attachment device

[0041] Figure 1 This is a schematic diagram of a particle attachment device according to an embodiment of the present invention.

[0042] like Figure 1As shown, the particle attachment device 100 includes a holder 10, a chamber 20, a nozzle 30, an inlet 40, and a flow control component 50. The holder 10 holds a filter substrate 70 having a first end face 71a from which fluid can flow and a second end face 71b from which fluid can flow. The chamber 20 communicates with the holder 10 and is arranged such that the first end face 71a of the filter substrate 70 faces the space within the chamber 20. The nozzle 30 is disposed on the opposing surface 21 of the chamber 20, which faces the first end face 71a of the filter substrate 70, and is capable of spraying an aerosol containing particles onto the first end face 71a of the filter substrate 70. The inlet 40 is provided on the opposing surface 21 of the chamber 20 and is capable of drawing in ambient gas. The flow control component 50 is disposed on the opposing surface 21 where the inlet 40 is provided and is capable of controlling the flow of ambient gas. By configuring the structure in this way, the flow of the surrounding gas can be controlled by the flow control component 50 to generate a swirling flow in the fluid within the chamber 20, thereby promoting the diffusion of particles in the fluid (aerosol) within the chamber 20. As a result, in a cross section orthogonal to the flow direction of the fluid, the difference in the amount of particle diffusion between the central region and the outer peripheral region becomes smaller, thus enabling the formation of a trapping layer of uniform thickness.

[0043] The following is a detailed description of each component of the filter substrate 70 forming the trapping layer and the particle attachment device 100.

[0044] <Filter substrate 70>

[0045] As for the filter substrate 70, it is not particularly limited as long as it has a first end face 71a through which fluid can flow and a second end face 71b through which fluid can flow. Various shapes of components can be used. For example, the filter substrate 70 can be a wall-flow columnar honeycomb substrate. A columnar honeycomb structure filter made using a wall-flow columnar honeycomb substrate can be used as a DPF and GPF for collecting PM such as soot from combustion devices, typically installed on the exhaust gas line of a vehicle engine.

[0046] Here, a schematic cross-sectional view (a cross-sectional view parallel to the direction of cell extension) and an end view (an end view of the first end face) of the wall-flow columnar honeycomb substrate are shown. Figure 2 And 3.

[0047] like Figure 2As shown in Figure 3, the columnar honeycomb substrate 72 has a plurality of first cells 74 and a plurality of second cells 75. The first cells 74 extend from a first end face 71a to a second end face 71b, with the first end face 71a open and the second end face 71b having a sealing portion 73. The second cells 75 extend from the first end face 71a to the second end face 71b, with the second end face 71b open and the first end face 71a having a sealing portion 73. In addition, the columnar honeycomb substrate 72 also has an outer peripheral wall 76 on the outside of the first cells 74 and the second cells 75, and a porous partition wall 77 is provided between the first cells 74 and the second cells 75. The first cells 74 and the second cells 75 are alternately arranged adjacent to each other through the porous partition wall 77, thereby making the first end face 71a and the second end face 71b honeycomb-shaped.

[0048] The size of the columnar honeycomb substrate 72 is not particularly limited, and it can have a diameter of 180 mm or more in a cross-section orthogonal to the direction in which the first cell 74 and the second cell 75 extend. For columnar honeycomb substrates 72 with a diameter of 180 mm or more, it is difficult to form a trapping layer of uniform thickness using conventional trapping layer forming apparatus. In contrast, by using the particle attachment apparatus 100 of the embodiment of the present invention, a trapping layer of uniform thickness can be formed.

[0049] In this specification, the term "diameter" refers to the equivalent circular diameter when the cross-section of the columnar honeycomb substrate 72 is not circular.

[0050] There are no particular limitations on the materials constituting the columnar honeycomb substrate 72, and ceramics can be cited as examples. Examples of ceramics include cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indianite, pseudosapphire, corundum, titanium dioxide, and silicon nitride. These ceramics can be used alone or in combination of two or more.

[0051] The end face shape of the columnar honeycomb substrate 72 is not particularly limited. For example, it can be a circular, elliptical, racetrack-shaped, or oblong arc shape, or a polygonal shape such as a triangle or quadrilateral. It should be noted that the columnar honeycomb substrate 72 shown in the figure is an example with a circular end face shape.

[0052] The shape of the perforations in the cross-section orthogonal to the direction extending from the perforations (first perforation 74 and second perforation 75) is not particularly limited, but is preferably quadrilateral, hexagonal, octagonal, or a combination thereof. Among these, quadrilaterals (especially squares) and hexagons are preferred. By forming the perforation shape in this way, the pressure loss when fluid flows in the columnar honeycomb structure filter can be reduced.

[0053] From the viewpoint of suppressing pressure loss, the upper limit of the average thickness of the porous partition 77 is preferably 0.238 mm or less, more preferably 0.228 mm or less, and even more preferably 0.220 mm or less. However, from the viewpoint of ensuring the strength of the columnar honeycomb substrate 72, the lower limit of the average thickness of the porous partition 77 is preferably 0.194 mm or more, more preferably 0.204 mm or more, and even more preferably 0.212 mm or more.

[0054] The thickness of the porous partition 77 refers to the length of the line segment that connects the centroids of adjacent pores in a cross section orthogonal to the direction of extension of the pore grids (first pore grid 74, second pore grid 75). The average thickness of the porous partition 77 refers to the average thickness of all the porous partitions 77.

[0055] The pore density (number of pores per unit cross-sectional area) of the columnar honeycomb substrate 72 is not particularly limited, and can be, for example, 6 to 2000 pores per square inch (0.9 to 311 pores per cm²). 2 Preferably, the number of holes is 50–1000 per square inch (7.8–155 holes per cm). 2 More preferably, it is 100–400 holes / square inch (15.5–62.0 holes / cm²). 2 ).

[0056] The columnar honeycomb substrate 72 can be provided as a one-piece molded article. Alternatively, the columnar honeycomb substrate 72 can also be provided as a unit assembly in which multiple columnar honeycomb units, each having an outer peripheral wall, are joined together by side connections. By providing the columnar honeycomb substrate 72 as a unit assembly, thermal shock resistance can be improved.

[0057] The columnar honeycomb substrate 72 can be manufactured using methods known in the art. The following describes an illustrative method for manufacturing the columnar honeycomb substrate 72.

[0058] First, a raw material composition containing ceramic raw materials, a dispersion medium, a pore-forming material, and a binder is mixed to form a blank. This blank is then extruded to form the desired columnar honeycomb structure. Additives such as dispersants can be added to the raw material composition as needed. During extrusion molding, a die with the desired overall shape, pore shape, partition wall thickness, and pore density can be used.

[0059] After drying the columnar honeycomb molded body, sealing portions are formed at specified positions on both ends of the columnar honeycomb molded body. Then, the sealing portions are dried to obtain a columnar honeycomb molded body with sealing portions. Subsequently, the columnar honeycomb molded body is degreased and fired to obtain a columnar honeycomb structure (columnar honeycomb substrate 72).

[0060] Ceramic raw materials are those materials that remain after firing and serve as the framework for the columnar honeycomb structure of ceramics. As ceramic raw materials, materials capable of forming the aforementioned ceramics after firing can be used. Ceramic raw materials can be provided, for example, in powder form. Examples of ceramic raw materials include cordierite, mullite, zircon, aluminum titanate, silicon carbide, silicon nitride, zirconium oxide, spinel, Indian quartz, pseudosapphire, corundum, and titanium dioxide, among others. Specific examples of such raw materials are not limited, but include silicon dioxide, talc, alumina, kaolin, serpentine, pyrophyllite, brucite, boehmite, mullite, magnesite, and aluminum hydroxide. Two or more ceramic raw materials can be used alone or in combination.

[0061] In the case of columnar honeycomb structure filters used for DPF and GPF, cordierite is preferably used as the ceramic. In this case, cordierite-modified raw materials can be used as the ceramic raw material. Cordierite-modified raw materials refer to raw materials that become cordierite through firing. Cordierite-modified raw materials preferably have the following chemical composition: alumina (Al₂O₃) (including aluminum hydroxide components converted to alumina): 30–45% by mass, magnesium oxide (MgO): 11–17% by mass, and silicon dioxide (SiO₂): 42–57% by mass.

[0062] Examples of suitable dispersion media include water or mixtures of water and organic solvents such as alcohols, with water being particularly preferred.

[0063] As a pore-forming material, there are no particular limitations as long as the material becomes porous after firing. Examples include wheat flour, starch, foaming resin, water-absorbing resin, porous silica, carbon (e.g., graphite), ceramic spheres, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic acid, and phenol. Two or more pore-forming materials can be used alone or in combination. From the viewpoint of increasing the porosity of the fired body, the content of the pore-forming material relative to 100 parts by mass of the ceramic raw material is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more. From the viewpoint of ensuring the strength of the fired body, the content of the pore-forming material relative to 100 parts by mass of the ceramic raw material is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 4 parts by mass or less.

[0064] Examples of adhesives include organic adhesives such as methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. In particular, it is preferable to use a combination of methylcellulose and hydroxypropyl methylcellulose as an adhesive. Furthermore, from the viewpoint of improving the strength of the honeycomb molded body, the adhesive content relative to 100 parts by weight of the ceramic raw material is preferably 4 parts by weight or more, more preferably 5 parts by weight or more, and even more preferably 6 parts by weight or more. From the viewpoint of suppressing cracking caused by abnormal heating during the firing process, the adhesive content relative to 100 parts by weight of the ceramic raw material is preferably 9 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 7 parts by weight or less. Two or more adhesives can be used alone or in combination.

[0065] Ethylene glycol, dextrin, fatty acid soaps, polyether polyols, etc., can be used as dispersants. Dispersants can be used alone or in combination of two or more. The content of the dispersant relative to 100 parts by weight of the ceramic raw material is preferably 0 to 2 parts by weight.

[0066] There are no particular limitations on the method for sealing the end faces of the columnar honeycomb structure; known methods can be used. There are no particular limitations on the material of the sealing portion 73, but ceramic is preferred from the viewpoint of strength and heat resistance. As the ceramic, a ceramic material containing at least one selected from cordierite, mullite, zircon, aluminum titanate, silicon carbide, silicon nitride, zirconium oxide, spinel, Indian stone, pseudosapphire, corundum, and titanium dioxide is preferred. To ensure uniform expansion rates during firing and to contribute to improved durability, it is further preferable that the sealing portion 73 be made of the same material as the main body of the columnar honeycomb structure.

[0067] After drying the honeycomb molded body, degreasing and firing are performed to manufacture a columnar honeycomb structure (columnar honeycomb substrate 72). The conditions for the drying, degreasing and firing processes can be well-known conditions based on the material composition of the honeycomb molded body, and no special explanation is required. Examples of specific conditions are listed below.

[0068] In the drying process, conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying can be used. Among these, from the viewpoint of being able to dry the entire columnar honeycomb structure quickly and uniformly, a combination of hot air drying and microwave drying or dielectric drying is preferred.

[0069] When forming the sealing portions, it is preferable to dry the sealing portions after forming them on both ends of the dried columnar honeycomb molded body. The sealing portions are formed at predetermined positions such that a plurality of first cells and a plurality of second cells are alternately arranged adjacent to each other with porous partitions, the plurality of first cells extending from a first end face to a second end face and having an opening on the first end face and a sealing portion on the second end face, and the plurality of second cells extending from the first end face to the second end face and having an opening on the second end face and a sealing portion on the first end face.

[0070] Next, the degreasing process will be explained. The combustion temperature of the adhesive is around 200℃, and the combustion temperature of the pore-forming material is around 300–1000℃. Therefore, the degreasing process only requires heating the columnar honeycomb molded body to a temperature range of around 200–1000℃. The heating time is not particularly limited, but is typically around 10–100 hours. The columnar honeycomb molded body after the degreasing process is called the pre-burned body.

[0071] The firing process also depends on the material composition of the columnar honeycomb molded body. For example, it can be carried out by heating the pre-fired body to 1350-1600°C and holding it for 3-10 hours. In this way, a columnar honeycomb structure (columnar honeycomb substrate 72) with multiple first cells 74 and multiple second cells 75 can be produced. The first cells 74 extend from a first end face 71a to a second end face 71b. The first end face 71a is open and has a sealing portion 73 on the second end face 71b. The second cells 75 extend from the first end face 71a to the second end face 71b. The second end face 71b is open and has a sealing portion 73 on the first end face 71a. The first cells 74 and the second cells 75 are arranged alternately adjacent to each other with porous partitions 77.

[0072] <Retainer 10>

[0073] The retainer 10 is a component that holds the filter substrate 70. The retainer 10 is configured to hold the filter substrate 70 in a position opposite to the nozzle 30 with its first end face 71a exposed. In one embodiment, the retainer 10 may have a clamping mechanism 11 for holding the filter substrate 70 (e.g., the outer peripheral wall 76 of the columnar honeycomb substrate 72). The clamping mechanism 11 is not particularly limited, but a balloon clamp can be exemplified. The retainer 10 has a housing 12 for rectifying the aerosol passing through the filter substrate 70 in one direction without diffusion.

[0074] The material used for the retainer 10 can be, for example, metal or ceramic. Examples of metals include stainless steel, titanium alloy, copper alloy, aluminum alloy, and brass. For reasons of high durability and reliability, stainless steel is preferred for the retainer 10.

[0075] <Cavity 20>

[0076] The chamber 20 is a cylindrical or square tube-shaped component. The chamber 20 communicates with the retainer 10 and is arranged such that the first end face 71a of the filter substrate 70 faces the space inside the chamber 20.

[0077] The chamber 20 has a sidewall 22 connected to the retainer 10 and a surface (opposing surface 21) opposite to the first end face 71a of the filter substrate 70. The opposing surface 21 has an insertion port for the nozzle 30. With this structure, aerosol ejected from the nozzle 30 can be directly introduced into the chamber 20.

[0078] Materials used for chamber 20 can include metals, ceramics, etc. Examples of metals include stainless steel, titanium alloys, copper alloys, aluminum alloys, and brass. For reasons of high durability and reliability, stainless steel is preferred for chamber 20.

[0079] An intake 40 for taking in ambient gas is provided on the opposing surface 21 of the chamber 20. By taking in ambient gas from the intake 40 provided on the opposing surface 21, the ambient gas flows in the same direction as the flow direction of the aerosol ejected from the nozzle 30. Therefore, interference with the aerosol is eliminated, and the aerosol can be stabilized.

[0080] The shape of the entrance 40 is not particularly limited and can be a circle, an ellipse, a racetrack shape, an oblong shape, or a polygon such as a triangle or a quadrilateral.

[0081] The size and number of entrances 40 can be set appropriately according to the size of the opposing surface 21, without any special restrictions.

[0082] As the opposing surface 21, in one embodiment, a perforated plate and / or non-woven fabric can be used. Alternatively, in order to suppress the entry of agglomerated powder, fragments of the filter substrate 70, dust, etc., a filter can also be provided on the outer surface of the opposing surface 21.

[0083] When the cross-sectional area of ​​the flow path within the chamber 20, which is orthogonal to the flow direction of the aerosol, is larger than the first end face 71a of the filter substrate 70, a tapered portion 23 can be formed on the downstream side of the sidewall 22 in such a manner that the cross-sectional area of ​​the flow path gradually decreases toward the first end face 71a of the filter substrate 70. The contour of the downstream end of the tapered portion 23 preferably matches the outer peripheral contour of the first end face 71a of the filter substrate 70. With this structure, particles can be easily supplied to the first end face 71a of the filter substrate 70.

[0084] The distance from the outlet of the nozzle 30 to the first end face 71a of the filter substrate 70 is preferably designed based on the area of ​​the first end face 71a of the filter substrate 70. Specifically, since aerosols tend to diffuse uniformly in a direction orthogonal to the aerosol flow direction, it is preferable that the distance from the outlet of the nozzle 30 to the first end face 71a of the filter substrate 70 increases as the area of ​​the first end face 71a of the filter substrate 70 increases. In one embodiment, the distance from the outlet of the nozzle 30 to the first end face 71a of the filter substrate 70 can be 500 mm to 2000 mm.

[0085] <Nozzle 30>

[0086] As for nozzle 30, there are no particular limitations as long as it can spray aerosol containing particles toward the first end face 71a of filter substrate 70.

[0087] The nozzle 30 is preferably positioned and oriented to spray aerosol in a direction orthogonal to the first end face 71a of the filter substrate 70, and more preferably positioned and oriented to spray aerosol at the center of the first end face 71a of the filter substrate 70.

[0088] In one embodiment, it is preferred that the nozzle 30 is disposed at the center of the opposing surface 21, and that the opposing surface 21 around the nozzle 30 has a plurality of inlets 40. By adopting such a structure, the effect of promoting particle diffusion in the aerosol mixed with the surrounding gas within the chamber 20 can be improved.

[0089] <Flow control component 50>

[0090] The flow control component 50 is a component disposed on the opposing surface 21 (the inner surface of the opposing surface 21) where the inlet 40 is provided, and is capable of controlling the flow of the surrounding gas.

[0091] The flow control component 50 is not particularly limited as long as it has a structure that can control the flow of the surrounding gas, but it is preferable to have multiple blades 51 that can control the flow of the surrounding gas.

[0092] The tilt angle θ of the plurality of blades 51 relative to the opposing surface 21 is not particularly limited, but is preferably 80° or less, more preferably 70° or less, and even more preferably 60° or less. By controlling the tilt angle θ to such a value, the surrounding gas can be made to swirl, mixing efficiently with the aerosol ejected from the nozzle 30, thus promoting the diffusion of particles in the aerosol mixed with the surrounding gas. On the other hand, if the tilt angle θ becomes too small, particles tend to adhere to the blades 51, sometimes increasing material loss. Therefore, the tilt angle θ is preferably 10° or more, more preferably 15° or more, and even more preferably 30° or more.

[0093] When multiple blades 51 are provided on the opposing surface 21 where the inlet 40 is provided, only multiple blades 51 may be provided. However, from the viewpoint of ease of installation, a component with multiple blades 51 may also be provided.

[0094] Here, Figure 4 A schematic top view of a component having multiple blades 51 is shown. Additionally, Figure 5 A schematic enlarged cross-sectional view of the component in the circumferential direction (opposite surface 21 is also shown).

[0095] like Figure 4 and Figure 5 As shown, the component preferably having multiple blades 51 also has a planar portion 52 parallel to the opposing surface 21 and multiple openings 53 disposed on the planar portion 52, exposing at least a portion of the access port 40. The multiple blades 51 are disposed at the boundary between the planar portion 52 and the openings 53 and are inclined toward the openings 53. In addition, the multiple blades 51 preferably have a shape that is substantially the same as the outer edge shape of the openings 53. If the component has such a shape, for plate-shaped components, after forming cuts in the openings 53 and the portion that forms the multiple blades 51 (excluding the boundary between the planar portion 52 and the openings 53), the cut portions can be easily pushed out, thereby enabling easy manufacturing.

[0096] In one configuration, multiple blades 51 can be arranged in two or more rows radially from the center of the opposing surface 21 toward the outer periphery. This structure enhances the effect of creating a swirling flow in the surrounding gas.

[0097] Materials used for the flow control component 50 can include, for example, metals and ceramics. Examples of metals include stainless steel, titanium alloys, copper alloys, aluminum alloys, and brass. For reasons of high durability and reliability, stainless steel is preferred for the flow control component 50.

[0098] like Figure 6 As shown, the particle attachment device 100 according to an embodiment of the present invention may also include an aerosol generator 60 connected to the nozzle 30. The method of connecting the nozzle 30 and the aerosol generator 60 is not particularly limited; for example, it can be connected via a connecting pipe 61. By using the aerosol generator 60, aerosol can be stably supplied to the nozzle 30.

[0099] The aerosol generator 60 is a device that ejects particles along with a fluid (driving gas). There is no particular limitation on the type of aerosol generator 60; aerosol generators known in the art can be used. For example, an aerosol generator 60 with a mechanism that utilizes negative pressure generated by a high-speed fluid to attract particles and expel them along with the fluid can be used.

[0100] As the fluid (driving gas), the spray flow rate of the aerosol ejected from the nozzle 30 can be controlled by using a compressed gas such as pressure-adjusted compressed air. Furthermore, as the driving gas, dry air (e.g., with a dew point below 10°C) is preferably used to suppress particle aggregation.

[0101] In the aerosol generator 60, to reduce wear caused by friction from contact with particles, it is preferable to form a layer of material composed of diamond, DLC (diamond-like carbon), titanium nitride (TiN), titanium carbonitride (TiCN), silicon carbonitride (SiCN), silicon carbide (SiC), silicon nitride (SiN), superhard materials, or alloys or combinations thereof on the surface in contact with the particles. This layer can be formed by coating, plating, lining, etc.

[0102] Here, Figure 7 A specific example of an aerosol generator 60 is shown.

[0103] Figure 7 The aerosol generator 420 shown has:

[0104] Drive gas flow path 427, which is used to allow pressurized drive gas to flow;

[0105] The supply port 427i is located in the middle of the driving gas flow path 427 and can attract particles (e.g., ceramic particles 422) from the outer periphery of the driving gas flow path 427 toward the driving gas flow path 427.

[0106] Nozzle 421, which is installed at the front end of the driving gas flow path 427, is capable of spraying aerosol;

[0107] Flow path 423, which is used to attract and transport ceramic particles 422, and has an outlet 423e communicating with the supply port 427i; and

[0108] The containment section 429 is used to contain ceramic particles 422 and to supply ceramic particles 422 to the flow path 423 for attraction and transport.

[0109] The receiving section 429 can be, for example, a funnel. Ceramic particles 422, adjusted to a predetermined particle size distribution, are received within the receiving section 429. The ceramic particles 422 received in the receiving section 429 are attracted by the driving gas flow path 427 and transported from the outlet 429e located at the bottom of the receiving section 429 through the flow path 423 to the outlet 423e, and then introduced into the driving gas flow path 427 through the supply port 427i. At this time, the surrounding gas (typically air) attracted from the inlet 429i of the receiving section is also introduced into the driving gas flow path 427 along with the ceramic particles 422 through the flow path 423. The outlet 423e and the supply port 427i are common. Furthermore, the ceramic particles 422 are introduced into the driving gas flow path 427 from a direction substantially perpendicular to the flow direction of the driving gas flowing through the driving gas flow path 427.

[0110] Ceramic particles 422 supplied to the driving gas flow path 427 collide with the driving gas flowing in the driving gas flow path 427, breaking down and mixing to form an aerosol, which is then ejected from the nozzle 421. The nozzle 421 is preferably positioned and oriented to eject the aerosol in a direction perpendicular to the bottom surface of the columnar honeycomb structure's inlet side. More preferably, the nozzle 421 is positioned and oriented to eject the aerosol toward the center of the bottom surface of the inlet side in a direction perpendicular to the bottom surface of the inlet side.

[0111] The supply of ceramic particles 422 to the receiving section 429 is not limited, and for example, a powder metering machine 4211 such as a screw feeder and a belt conveyor is preferably used. The ceramic particles 422 discharged from the powder metering machine 4211 can fall into the receiving section 429 by gravity.

[0112] In a preferred embodiment, the driving gas flow path 427 has a venturi section 427v where the flow path narrows midway, and the supply port 427i is located downstream of the narrowest point in the venturi section 427v. Because the driving gas flow path 427 has a venturi section 427v, the velocity of the driving gas passing through the venturi section 427v increases, allowing the higher-velocity driving gas to collide with the ceramic particles 422 supplied downstream of the venturi section 427v, thus increasing the crushing force. To further enhance the crushing force generated by the driving gas, it is more preferable that the supply port 427i is located downstream of and adjacent to the narrowest point in the venturi section 427v. This configuration can be achieved, for example, by connecting the driving gas flow path 427 and the flow path 423 for suction and delivery using a venturi injector 4210.

[0113] From the viewpoint of improving the crushing force of ceramic particles, the lower limit of the flow velocity of the driving gas before passing through the Venturi section 427v is preferably 13 m / s or more, more preferably 20 m / s or more, and even more preferably 26 m / s or more. The upper limit of the flow velocity of the driving gas before passing through the Venturi section 427v is not specifically set, and is usually 50 m / s or less, typically 40 m / s or less.

[0114] From the viewpoint of improving crushing force, the lower limit of the ratio of the flow path cross-sectional area immediately preceding the Venturi section 427v to the flow path cross-sectional area of ​​the Venturi section 427v is preferably 8 or more, more preferably 16 or more. There is no particular limit to the upper limit of the ratio of the flow path cross-sectional area immediately preceding the Venturi section 427v to the flow path cross-sectional area of ​​the Venturi section 427v, but if it is too large, the pressure drop of the Venturi section 427v will increase; therefore, it is preferably 64 or less, more preferably 32 or less. Here, the flow path cross-sectional area of ​​the Venturi section 427v refers to the flow path cross-sectional area at the narrowest part of the flow path in the Venturi section 427v. Furthermore, the flow path cross-sectional area immediately preceding the Venturi section 427v refers to the flow path cross-sectional area upstream of the Venturi section 427v before the flow path narrows.

[0115] If a Venturi injector 4210 is used, for example, when the driving gas flows through the driving gas flow path 427, a large attraction force can be applied to the suction and conveying flow path 423, preventing the suction and conveying flow path 423 from being blocked by ceramic particles 422. The Venturi injector 4210 is also effective as a unit for removing ceramic particles 422 when the suction and conveying flow path 423 is blocked by ceramic particles 42b.

[0116] The spray flow rate of the aerosol ejected from nozzle 421 can be controlled by using a compressed gas such as pressure-adjusted compressed air as the driving gas. Dry air (e.g., with a dew point below 10°C) is preferably used as the driving gas to suppress the agglomeration of ceramic particles.

[0117] The fine ceramic particles 422 have the property of easily agglomerating. However, by using the aerosol generator 420 of this embodiment, it is possible to spray ceramic particles 422 with a target particle size distribution whose agglomeration can be suppressed.

[0118] like Figure 8 As shown, the particle attachment device 100 of this embodiment may further include a blower 65 for applying an attractive force to the second end face 71b of the filter substrate 70. The blower 65 can be connected to the retainer 10 via an exhaust pipe 66. By using the blower 65, the flow rate of the surrounding gas flowing into the chamber 20 can be adjusted according to the attractive force from the blower 65.

[0119] Blower 65 is a device with an exhaust function. There is no particular limitation on the type of blower 65, and blowers known in the art can be used.

[0120] It should be noted that a flow meter (not shown) can also be installed on the exhaust pipe 66 to monitor the gas flow rate measured by the flow meter, and the strength of the blower 65 can be controlled according to the gas flow rate.

[0121] (2) Filter manufacturing method

[0122] The filter manufacturing method according to an embodiment of the present invention is performed using a particle attachment device 100. The particle attachment device 100 can control the flow of surrounding gas via a flow control member 50 to generate a swirling flow in the fluid within the chamber 20, thereby promoting the diffusion of particles in the fluid (aerosol) within the chamber 20. Therefore, by using the particle attachment device 100, a filter having a trapping layer of uniform thickness can be manufactured.

[0123] In one embodiment of the present invention, the method for manufacturing a filter includes a step of holding a filter substrate 70 in a holder 10 (hereinafter referred to as the "holding step") and a step of spraying aerosol from a nozzle 30 toward a first end face 71a of the filter substrate 70 while controlling the flow of ambient gas drawn in from an inlet 40 provided on the opposing surface 21 of the chamber 20 using a flow control member 50, thereby causing particles to adhere to the filter substrate 70 (hereinafter referred to as the "particle adhesion step"). By implementing such steps, appropriate control of the particle adhesion device 100 can be achieved, thus enabling the manufacture of a filter having a trapping layer of uniform thickness.

[0124] During the holding process, the filter substrate 70 is positioned and held with its first end face 71a facing the space inside the chamber 20. The holding method is not particularly limited as long as it is appropriately set according to the type of holder 10.

[0125] In the particle attachment process, the flow of the surrounding gas can be controlled by the flow control component 50 to create a swirling flow in the fluid within the chamber 20. Therefore, when the aerosol is sprayed from the nozzle 30 toward the first end face 71a of the filter substrate 70, the swirling flow of the surrounding gas promotes particle diffusion. Thus, before reaching the first end face 71a of the filter substrate 70, the particles can be uniformly dispersed in the aerosol mixed with the surrounding gas. As a result, the particles are uniformly supplied to the entire first end face 71a of the filter substrate 70 facing the space within the chamber 20, forming a trapping layer of uniform thickness. For example, in the case where the filter substrate 70 is a columnar honeycomb substrate 72, the particles are drawn into the first pore 74 opening in the first end face 71a, and the particles drawn into the first pore 74 adhere to the surface of the first pore 74 to form a trapping layer.

[0126] From the viewpoint of improving the film thickness stability of particles attached to the surface of the first pore 74, in the particle attachment process, the average flow velocity of the aerosol flowing in the chamber 20 is preferably 0.5 m / s to 3.0 m / s, more preferably 1.0 m / s to 2.0 m / s.

[0127] From the viewpoint of improving the film thickness stability of particles attached to the surface of the first pore 74, in the particle attachment process, the lower limit of the average flow velocity of the aerosol flowing within the columnar honeycomb substrate 72 is preferably 0.5 m / s or more, more preferably 1 m / s or more. Furthermore, in order to maintain the high porosity of the porous partition 77, the upper limit of the average flow velocity of the aerosol flowing within the columnar honeycomb substrate 72 is preferably 20 m / s or less, more preferably 15 m / s or less.

[0128] If the particle attachment process continues, the pressure loss between the first end face 71a and the second end face 71b of the filter substrate 70 will increase as the amount of attached particles increases. Therefore, by pre-calculating the relationship between the amount of attached particles and the pressure loss, the end point of the particle attachment process can be determined based on the pressure loss. Therefore, the particle attachment device 100 can also be equipped with a differential pressure gauge to measure the pressure loss between the first end face 71a and the second end face 71b of the filter substrate 70, and the end point of the particle attachment process can be determined based on the value of the differential pressure gauge.

[0129] When the filter substrate 70 is a columnar honeycomb substrate 72, if a particle attachment process is performed, the particles will be attached to the first end face 71a of the columnar honeycomb substrate 72. Therefore, it is preferable to use a scraper or other clamp to flatten the first end face 71a while using a vacuum or the like to remove the particles.

[0130] There are no particular limitations on the particles contained in the aerosol, but ceramic particles are preferred.

[0131] The ceramic particles used as ceramic particles constitute the porous spacer 77. For example, ceramic particles containing one or more of the following can be used: cordierite, silicon carbide (SiC), talc, mica, mullite, ceramic shavings, aluminum titanate, alumina, silicon nitride, SiAlON, zirconium phosphate, zirconium oxide, titanium dioxide, and silicon dioxide. The main component of the ceramic particles is preferably silicon carbide, alumina, silicon dioxide, cordierite, or mullite. The main component of the ceramic particles refers to a component comprising 50% or more by mass. Preferably, the ceramic particles contain 50% or more by mass of SiC, more preferably 70% or more by mass, and even more preferably 90% or more by mass.

[0132] After the particle attachment process, the filter substrate 70 with the particles attached is heat-treated at a maximum temperature of 1000°C or higher for at least 1 hour, for example, for 1 to 6 hours, typically at a maximum temperature of 1100°C to 1400°C for 1 to 6 hours, thereby completing the filter. The heat treatment can be performed, for example, by placing the filter substrate 70 with the particles attached in an electric furnace or a gas furnace. Through heat treatment, the particles bond together and adhere to the filter substrate 70, forming a trapping layer. If the heat treatment is performed under oxygen-containing conditions such as air, an oxide film is generated on the particle surface, promoting particle bonding. This results in a trapping layer that is difficult to peel off from the filter substrate 70.

[0133] (3) honeycomb structure filter

[0134] Figure 9 This is a schematic cross-sectional view (parallel to the direction of pore extension) of a columnar honeycomb structure filter according to an embodiment of the present invention. Additionally, Figure 10 This is a schematic end view of the columnar honeycomb structure filter (end view of the first end face).

[0135] like Figure 9 As shown in Figure 10, the columnar honeycomb structure filter 200 of the embodiment of the present invention includes a columnar honeycomb substrate 72 and a trapping layer 80. The columnar honeycomb substrate 72 has a plurality of first cells 74 extending from a first end face 71a to a second end face 71b, with the first end face 71a open and the second end face 71b having a sealing portion 73, and a plurality of second cells 75 extending from the first end face 71a to the second end face 71b, with the second end face 71b open and the first end face 71a having a sealing portion 73. The first cells 74 and the second cells 75 are alternately arranged adjacent to each other with porous partition walls 77 in between. The trapping layer 80 is formed on the surface of the first cells 74. It should be noted that, in Figure 9 and 10 The example shown is an example in which a trapping layer 80 is formed on the surface of the first aperture 74, but the trapping layer 80 may also be formed on the surface of the second aperture 75 or on both the surfaces of the first aperture 74 and the second aperture 75.

[0136] In the embodiment of the present invention, the thickness difference of the collection layer 80 of the columnar honeycomb structure filter 200 is 15 μm or less, preferably 13 μm or less. If the difference is within this range, the collection layer 80 can be made to have a uniform thickness, thereby improving the collection effect of particulate matter (PM).

[0137] The thickness of the trapping layer 80 tends to vary, particularly between the central and peripheral portions, in the cross-section of the columnar honeycomb filter 200, which extends orthogonally to the directions of the first and second pores 74 and 75. Therefore, the thickness difference of the trapping layer 80 is preferably calculated by determining the difference between the thickness of the central portion and the thickness of the peripheral portion in this cross-section. Here, the central portion refers to the portion in this cross-section extending from the center to one-third of the diameter (the distance from the center to the periphery), and the peripheral portion refers to the portion extending from the periphery to one-third of the diameter.

[0138] The thickness of the trapping layer 80 can be measured using a 3D measuring machine (model VR-3200 or VR-5200) manufactured by KEYENCE Co., Ltd. The measurement can be performed at a position 25 mm from the end face (first end face 71a, second end face 71b) in the direction extending from the hole grid (first hole grid 74 and second hole grid 75).

[0139] In the columnar honeycomb structure filter 200 of this invention, when exhaust gas containing particulate matter (PM) such as soot is supplied to the first end face 71a of the columnar honeycomb structure filter 200, the exhaust gas is introduced into the first pore cell 74 and proceeds downstream within the first pore cell 74. The first pore cell 74 has a sealing portion 73 on the downstream side of the second end face 71b, so the exhaust gas flows into the second pore cell 75 through a porous partition 77 with a trapping layer 80 that divides the first pore cell 74 and the second pore cell 75. The particulate matter cannot pass through the porous partition 77 with the trapping layer 80, so it is trapped and accumulates in the first pore cell 74. After the particulate matter is removed, the clean exhaust gas flowing into the second pore cell 75 proceeds downstream within the second pore cell 75 and flows out from the downstream side of the second end face 71b.

[0140] The columnar honeycomb structure filter 200 of the embodiment of the present invention preferably has a diameter of 180 mm or more in a cross-section orthogonal to the direction in which the first pore 74 and the second pore 75 extend. In conventional particle attachment devices, it is difficult to form a trapping layer 80 of uniform thickness for a columnar honeycomb substrate 72 with a diameter of 180 mm or more. In contrast, in the particle attachment device 100 of the embodiment of the present invention, a trapping layer 80 of uniform thickness can be formed even for a columnar honeycomb substrate 72 with a diameter of 180 mm or more.

[0141] The columnar honeycomb structure filter 200 of the present invention can be manufactured using a columnar honeycomb substrate 72 as the filter substrate 70 and in accordance with the filter manufacturing method described above.

[0142] Example

[0143] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples in any way.

[0144] (A) Manufacturing of columnar honeycomb substrate

[0145] To prepare clay, 3 parts by mass of pore-forming material, 55 parts by mass of dispersion medium, 6 parts by mass of organic binder, and 1 part by mass of dispersant were added to 100 parts by mass of cordierite petrochemical raw material, followed by mixing and kneading. Alumina, aluminum hydroxide, kaolin, talc, and silica were used as the cordierite petrochemical raw material. Water was used as the dispersion medium, a water-absorbing polymer as the pore-forming material, hydroxypropyl methylcellulose as the organic binder, and fatty acid soap as the dispersant.

[0146] The clay is fed into an extrusion molding machine and extruded through a die of a specified shape to obtain a cylindrical honeycomb molded body. After dielectric drying and hot air drying, the two ends of the honeycomb molded body are cut off to a specified size to obtain a dried honeycomb body.

[0147] The obtained honeycomb dried body was sealed with cordierite as material in an alternating arrangement of first and second cells. Then, it was heated and degreased at about 200°C in an atmospheric atmosphere, and then fired at 1420°C for 5 hours in an atmospheric atmosphere to obtain columnar honeycomb substrate.

[0148] The specifications of the columnar honeycomb substrate are as follows.

[0149] Overall shape: Cylindrical, 270mm in diameter × 300mm in height

[0150] The shape of the perforation in a section orthogonal to the direction of perforation extension: square

[0151] Pore ​​density (number of pores per unit cross-sectional area): 200 pores / square inch (31.1 pores / cm²) 2 )

[0152] Thickness of porous partition wall: 0.2 mm (nominal value based on die specifications)

[0153] (B) Manufacturing of columnar honeycomb structure filters

[0154] For the above-mentioned columnar honeycomb substrate, using Figure 8 The particle attachment device shown uses a flow control component to control the flow of ambient gas drawn in from an inlet located on the opposite side of the chamber, while spraying an aerosol containing ceramic particles from a nozzle toward the first end face of the columnar honeycomb substrate, so that the ceramic particles adhere to the surface of the first pore of the columnar honeycomb substrate.

[0155] The specifications and operating conditions of the particle attachment device are as follows.

[0156] <Flow control components>

[0157] structure: Figure 4 The flow control component shown has two rows of blades arranged radially from the center of the opposing surface toward the outer periphery.

[0158] The blade's tilt angle θ relative to the opposing surface: 15–60° (the specific tilt angle θ in each embodiment is shown in Table 1. It should be noted that no flow control component was used in Comparative Example 1.)

[0159] <cavity>

[0160] Shape: Cylindrical

[0161] Inner diameter: 300mm

[0162] Length: 850mm

[0163] Surrounding gas: air

[0164] Structure of opposing surfaces: perforated plate

[0165] Inlet filter settings: Yes

[0166] Nozzle position: Center of the opposing surface

[0167] Distance from nozzle exit to the first end face of columnar honeycomb substrate: 850mm

[0168] <Aerosol generator>

[0169] Product Name: None (Made by our company) (Features) Figure 7 (Structure shown)

[0170] Type: Continuous aerosol generator

[0171] Connection method of the driving gas flow path and the flow path used for suction and delivery: Venturi ejector

[0172] The ceramic particle supply port is located downstream of and adjacent to the narrowest point of the flow path in the venturi section.

[0173] Method for supplying ceramic particles to the containment section: screw feeder

[0174] Types of containment units: funnel

[0175] Types of ceramic particles contained in the containment section: SiC particles

[0176] Volumetric particle size distribution of ceramic particles (determined by laser diffraction-scattering): median particle size (D50) = 3 μm; SiC particles with a particle size greater than 10 μm: ≤20% by volume.

[0177] Driven gas: Compressed dry air (dew point below 10°C)

[0178] The surrounding gas that is attracted: air

[0179] Average flow rate of the surrounding gas flowing in the flow path used for suction and delivery: 40 L / min

[0180] Average flow rate of the driving gas in the driving gas path before merging with the attracted surrounding gas: 80 L / min

[0181] The ratio of the flow path cross-sectional area immediately preceding the Venturi to the flow path cross-sectional area of ​​the Venturi itself is 1:0.028.

[0182] Average flow velocity of aerosol ejected from the nozzle: 26 m / s (measured by ANEMOMASTER [KANOMAX type: 6162] at a position 10-20 mm downstream of the nozzle)

[0183] Average flow rate of aerosol ejected from the nozzle: 120 L / min (measured by a flow meter)

[0184] The mass flow rate of ceramic particles in the aerosol ejected from the nozzle is 0.5 g / s (measured by a flow meter).

[0185] Operating Conditions

[0186] Blower suction flow rate: 4000L / min

[0187] The average flow velocity of the aerosol flowing within the columnar honeycomb substrate is approximately 10 m / s (calculated by dividing the flow rate by the cell opening area).

[0188] The end point of the ceramic particle adhesion process: the moment when the differential pressure gauge value reaches +0.1 kPa to +0.4 kPa (the differential pressure value varies depending on the membrane quality set according to the product volume).

[0189] Next, while using a scraper to flatten the first end face of the columnar honeycomb substrate with attached ceramic particles, the ceramic particles attached to the first end face are removed by vacuum suction. Then, the columnar honeycomb substrate is placed in an electric furnace and heated in an atmospheric atmosphere at a maximum temperature of 1200°C for 2 hours, thereby obtaining a columnar honeycomb structure filter with a trapping layer formed on the surface of the first cell.

[0190] For the columnar honeycomb structure filter obtained above, the thickness of the trapping layer in the center and the outer periphery is determined at a position 25 mm from the first end face in the direction extending from the first pore. The thickness is determined using a 3D measuring machine (model VR-3200 or VR-5200) manufactured by KEYENCE Corporation.

[0191] Furthermore, in the manufacturing of the aforementioned columnar honeycomb structure filter, the material loss during the ceramic particle attachment process is calculated. The material loss is calculated by subtracting the amount of ceramic particles attached to the columnar honeycomb substrate from the amount of ceramic particles supplied for forming the trapping layer. The amount of ceramic particles supplied for forming the trapping layer is the amount of ceramic particles supplied by the screw feeder. Additionally, the amount of ceramic particles attached to the columnar honeycomb substrate is calculated from the mass difference of the columnar honeycomb substrate before and after the formation of the trapping layer.

[0192] The evaluation results are shown in Table 1.

[0193] [Table 1]

[0194]

[0195] As shown in Table 1, the thickness difference between the center and outer periphery of the trapping layer formed using a particle attachment device without flow control components is large (Comparative Example 1), while the thickness difference between the center and outer periphery of the trapping layer formed using a particle attachment device with flow control components is small (Examples 1-4). Furthermore, the smaller the tilt angle θ of the blades of the flow control component, the easier it is for ceramic particles to adhere to the blades, thus tending to increase material loss.

[0196] As can be seen from the above results, according to the present invention, a particle attachment device and a method for manufacturing a filter can be provided that can form a trapping layer of uniform thickness regardless of the type or size of the filter substrate. Furthermore, according to the present invention, a columnar honeycomb structure filter having a trapping layer of uniform thickness can be provided.

[0197] Symbol Explanation

[0198] 10: Holder; 20: Chamber; 21: Opposing surface; 22: Side wall; 23: Conical part; 30: Nozzle; 40: Inlet / outlet; 50: Flow control component; 51: Blade; 52: Flat part; 53: Opening; 60: Aerosol generator; 61: Connecting pipe; 65: Blower; 66: Exhaust pipe; 70: Filter substrate; 71a: First end face; 71b: Second end face; 72: Columnar honeycomb substrate; 73: Sealing part; 74: First pore; 75: Second pore; 7 6: Outer wall; 77: Porous partition wall; 80: Capture layer; 100: Particle attachment device; 200: Columnar honeycomb structure filter; 420: Aerosol generator; 421: Nozzle; 422: Ceramic particles; 423: Flow path; 423e: Outlet; 427: Driving gas flow path; 427i: Supply port; 427v: Venturi section; 429: Receiving section; 429i: Inlet; 429e: Outlet; 4210: Venturi injector; 4211: Powder metering feeder.

Claims

1. A particle attachment device, comprising: A retainer for holding a filter substrate having a first end face through which fluid can flow in and a second end face through which the fluid can flow out. A chamber, which communicates with the retainer, is configured such that the first end face of the filter substrate faces the space within the chamber. A nozzle, disposed on the opposing surface of the chamber to the first end face of the filter substrate, is capable of spraying an aerosol containing particles toward the first end face of the filter substrate. An inlet, located on the opposite side of the chamber, is capable of drawing in surrounding gas, and A flow control component, disposed on the opposing surface where the intake is provided, has multiple blades capable of controlling the flow of the surrounding gas. The plurality of blades have an inclination angle of 10 to 80° relative to the opposing surface. The flow control component also has a planar portion parallel to the opposing surface and a plurality of openings disposed on the planar portion and exposing at least a portion of the intake port. The blade is disposed at the boundary between the planar portion and the opening portion and is inclined toward the opening portion.

2. The particle attachment device according to claim 1, wherein, The plurality of blades have an inclination angle of 15 to 70° relative to the opposing surface.

3. The particle attachment device according to claim 1, wherein, The plurality of blades have an inclination angle of 30 to 60° relative to the opposing surface.

4. The particle attachment device according to any one of claims 1 to 3, wherein, The blade has a shape that is substantially the same as the outer edge shape of the opening.

5. The particle attachment device according to any one of claims 1 to 3, wherein, The blades are arranged in two or more rows radially from the center of the opposing surface toward the outer periphery.

6. The particle attachment device according to claim 1 or 2, wherein, The nozzle is disposed at the center of the opposing surface, and the intake port is provided in multiple locations on the opposing surface surrounding the nozzle.

7. The particle attachment device according to claim 1 or 2, wherein, The filter substrate is a columnar honeycomb substrate, which has a plurality of first cells extending from the first end face to the second end face and having an opening on the first end face and a sealing portion on the second end face, and a plurality of second cells extending from the first end face to the second end face and having an opening on the second end face and a sealing portion on the first end face. The first cells and the second cells are alternately arranged adjacent to each other with porous partitions in between.

8. The particle attachment device according to claim 7, wherein, The columnar honeycomb substrate has a diameter of more than 180 mm in a cross section orthogonal to the direction in which the first and second cells extend.

9. The particle attachment device according to claim 1 or 2, wherein, The particle attachment device also includes an aerosol generator connected to the nozzle.

10. The particle attachment device according to claim 1 or 2, wherein, The particle attachment device also includes a blower for applying an attractive force to the second end face of the filter substrate.

11. The particle attachment device according to claim 1 or 2, wherein, The distance from the nozzle outlet to the first end face of the filter substrate is 500mm to 2000mm.

12. A method for manufacturing a filter, wherein, Use the particle attachment device according to any one of claims 1 to 11.

13. The method of manufacturing the filter according to claim 12, comprising: The process of holding the filter substrate in the holder, and The process of controlling the flow of the surrounding gas taken in from the inlet on the opposite surface of the chamber using the flow control component, and spraying the aerosol from the nozzle toward the first end face of the filter substrate to make the particles adhere to the filter substrate.

14. The method of manufacturing the filter according to claim 12 or 13, wherein, The particles are ceramic particles.

15. The method of manufacturing a filter according to claim 14, wherein, The main components of the ceramic particles are silicon carbide, alumina, silicon dioxide, cordierite, or mullite.

Images