CN116367906A - Particle attaching device, method for manufacturing filter, and columnar honeycomb structure filter - Google Patents

Abstract

The particle attachment device (100) is provided with a holder (10), a chamber (20), a nozzle (30), an inlet (40), and a flow control member (50). The holder (10) holds a filter substrate (70) having a first end face (71 a) and a second end face (71 b). The chamber (20) communicates with the holder (10) and is disposed such that the first end surface (71 a) of the filter substrate (70) faces the space in the chamber (20). The nozzle (30) is disposed on the facing surface (21) of the chamber (20) facing the first end surface (71 a) of the filter substrate (70) and can eject the aerosol containing particles toward the first end surface (71 a) of the filter substrate (70). The intake port (40) is provided on the facing surface (21) of the chamber (20) and can take in ambient gas. The flow control member (50) is disposed on the facing surface (21) provided with the intake port (40) and can control the flow of ambient gas.

Description

Particle attaching device, method for manufacturing filter, and columnar honeycomb structure filter

Technical Field

The present invention relates to a particle attachment device, a method for manufacturing a filter, and a columnar honeycomb filter.

Background

Particulate matter such as soot (hereinafter, referred to as PM Particulate Matter) is contained in exhaust gas discharged from an internal combustion engine such as a diesel engine or a gasoline engine. The soot is harmful to human body and the discharge is limited. Conventionally, in order to cope with exhaust gas restriction, a filter represented by DPF and GPF is widely used in which exhaust gas is passed through a porous partition wall having air permeability to filter PM such as soot.

As a filter for trapping PM, there is known a wall-flow type columnar honeycomb filter including a plurality of first cells extending from a first end surface to a second end surface and having openings at the first end surface and having plugged portions at the second end surface, and a plurality of second cells extending from the first end surface to the second end surface and having openings at the second end surface and having plugged portions at the first end surface, the first cells and the second cells being alternately arranged adjacent to each other with porous partition walls interposed therebetween.

In recent years, with the enhancement of exhaust gas regulations, more stringent emission standards of PM (PN limitation: number of particulate matters) have been introduced, and high trapping performance of PM (PN high trapping efficiency) has been demanded for filters. Therefore, it is known to form a layer for trapping PM (hereinafter referred to as "trapping layer") on the surface of porous partition walls forming cells.

As a device for forming a trapping layer, a device is proposed which has: a work fixing portion for fixing a base material of a honeycomb filter (hereinafter, simply referred to as "honeycomb base material"); a powder conveying unit which is disposed on one side of the workpiece fixing unit and conveys a powder (also referred to as "particles") by using a pressurized gas in a gas flow (also referred to as "fluid"); an introduction portion which is an unsealed space provided between the powder conveying portion and the workpiece fixing portion, and which introduces the powder conveyed by being carried by the air flow from the powder conveying portion into the honeycomb substrate fixed to the workpiece fixing portion by further mixing the powder with another air; and a suction unit disposed on the other side of the workpiece fixing unit, wherein the other side of the workpiece fixing unit is depressurized with respect to the one side of the workpiece fixing unit by using a suction means, and the gas passing through the honeycomb substrate fixed to the workpiece fixing unit is sucked (patent document 1). According to this device, the gas passing through the honeycomb substrate is attracted by the attraction unit, and thus the gas flow is rectified. By introducing the powder into the rectified gas flow to form a solid-gas two-phase flow, the powder can be uniformly and stably supplied to the honeycomb substrate, and therefore, a trapping layer having a uniform thickness can be formed.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5597148

Disclosure of Invention

Problems to be solved by the invention

The device described in patent document 1 is mainly suitable for forming a trapping layer on a honeycomb substrate having a small diameter (for example, a diameter of less than 140 mm), but when a trapping layer is formed on a honeycomb substrate having a large diameter (for example, a diameter of 180mm 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 large-thickness trapping layer is easily formed around the center portion of the honeycomb substrate, while a small-thickness trapping layer is formed near the outer peripheral portion of the honeycomb substrate. As a cause of this, it is assumed that in a cross section orthogonal to the flow direction of the fluid, the particles are supplied to the honeycomb substrate before sufficiently diffusing to the vicinity of the outer peripheral portion.

Patent document 1 assumes that a trapping layer is formed on a honeycomb substrate, but has the same problem that it is difficult to form a trapping layer of uniform thickness depending on the size of a filter substrate other than the honeycomb substrate.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a particle attaching device capable of forming a trapping layer of uniform thickness regardless of the type and size of a filter base material, and a method for manufacturing a filter.

In addition, an object of the present invention is to provide a columnar honeycomb structure filter having a trapping layer of uniform thickness.

Means for solving the problems

The present inventors have made intensive studies on the structure of a particle attachment device to solve the above-described problems, and as a result, have found that by providing a flow control member capable of controlling the flow of ambient gas at a specific position, swirling flow can be generated in a fluid in a chamber to promote the diffusion of particles, and completed the present invention.

That is, the present invention provides a particle attaching device comprising:

a holder for holding a filter substrate having a first end surface into which a fluid can flow and a second end surface from which the fluid can flow,

a chamber communicating with the holder, the chamber being disposed so that the first end surface of the filter substrate faces a space in the chamber,

a nozzle disposed on an opposite surface of the chamber to face the first end surface of the filter substrate, the nozzle being capable of ejecting an aerosol containing particles toward the first end surface of the filter substrate,

an intake port provided on the opposed surface of the chamber and capable of taking in ambient gas, and

And a flow control member which is disposed on the opposed surface provided with the intake port and is capable of controlling the flow of the ambient gas.

The present invention also provides a method for manufacturing a filter using the particle attachment device.

In addition, the present invention provides a columnar honeycomb filter having:

a columnar honeycomb substrate having a plurality of first cells extending from a first end face to a second end face and having openings in the first end face and sealing portions in the second end face, and a plurality of second cells extending from the first end face to the second end face and having openings in the second end face and sealing portions in the first end face, the first cells and the second cells being alternately arranged adjacent to each other with porous partition walls interposed therebetween, and

a trapping layer formed on a surface of at least one of the first cells and the second cells; wherein the difference in thickness of the trapping layer is 15 μm or less.

Effects of the invention

According to the present invention, it is possible to provide a particle attaching device capable of forming a trapping layer of uniform thickness without being affected by the type and size of a filter base material, and a method for manufacturing a filter.

In addition, according to the present invention, a columnar honeycomb structure filter having a trapping layer of uniform thickness can be provided.

Drawings

Fig. 1 is a schematic view of a particle attachment device according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of a columnar honeycomb substrate used in the particle attaching device of the embodiment of the present invention.

Fig. 3 is a schematic end view of the columnar honeycomb substrate of fig. 2.

FIG. 4 is a schematic top view of a component having a plurality of blades.

Fig. 5 is a schematic enlarged sectional view of the component of fig. 4 in the circumferential direction.

Fig. 6 is a schematic view of another particle attachment device according to an embodiment of the present invention.

Fig. 7 is a diagram schematically showing a specific example of the aerosol generator.

Fig. 8 is a schematic view of another particle attachment device according to an embodiment of the present invention.

Fig. 9 is a schematic cross-sectional view of a columnar honeycomb filter according to an embodiment of the present invention.

Fig. 10 is a schematic end view of the columnar honeycomb filter of fig. 9.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and it is to be understood that modifications, improvements, and the like, which are appropriately applied to the following embodiments based on common knowledge of those skilled in the art, are included in the scope of the present invention, without departing from the gist of the present invention.

(1) Particle attaching device

Fig. 1 is a schematic view of a particle attachment device according to an embodiment of the present invention.

As shown in fig. 1, the particle attachment apparatus 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 face 71a into 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 disposed such that the first end surface 71a of the filter substrate 70 faces the space in the chamber 20. The nozzle 30 is disposed on the facing surface 21 of the chamber 20 facing the first end surface 71a of the filter substrate 70, and can spray the aerosol containing particles toward the first end surface 71a of the filter substrate 70. The intake port 40 is provided on the facing surface 21 of the chamber 20, and can take in ambient gas. The flow control member 50 is disposed on the facing surface 21 provided with the inlet 40, and can control the flow of ambient gas. By adopting such a configuration, the flow control member 50 can control the flow of the ambient gas to generate a swirling flow in the fluid in the chamber 20, thereby promoting the diffusion of particles in the fluid (aerosol) in the chamber 20. As a result, the difference in the amount of diffusion of particles between the central region and the outer peripheral region becomes small in the cross section orthogonal to the flow direction of the fluid, and therefore, a trapping layer of uniform thickness can be formed.

The following describes in detail the components of the filter substrate 70 and the particle attachment device 100 that form the trapping layer.

< Filter substrate 70>

The filter base 70 is not particularly limited as long as it has a first end face 71a into which fluid can flow and a second end face 71b from which fluid can flow, and various shapes of members can be used. For example, the filter substrate 70 may be a wall-flow, columnar honeycomb substrate. A columnar honeycomb filter produced using a wall-flow type columnar honeycomb substrate can be used as a DPF or GPF for trapping PM such as soot, which is mounted on an exhaust gas line from a combustion device, typically an engine mounted on a vehicle.

Fig. 2 and 3 show schematic cross-sectional views (cross-sectional views parallel to the direction in which cells extend) and end-face views (end-face views of the first end face) of the wall-flow type columnar honeycomb substrate.

As shown in fig. 2 and 3, the columnar honeycomb substrate 72 includes a plurality of first cells 74 and a plurality of second cells 75, the first cells 74 extend from the first end face 71a to the second end face 71b, the first end face 71a is open and the second end face 71b has the plugged portions 73, the second cells 75 extend from the first end face 71a to the second end face 71b, and the second end face 71b is open and the first end face 71a has the plugged portions 73. The columnar honeycomb substrate 72 further includes outer peripheral walls 76 outside the first cells 74 and the second cells 75, and porous partition walls 77 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 with porous partition walls 77 interposed therebetween, whereby the first end face 71a and the second end face 71b are each honeycomb-shaped.

The size of the columnar honeycomb substrate 72 is not particularly limited, and may have a diameter of 180mm or more in a cross section orthogonal to the direction in which the first cells 74 and the second cells 75 extend. In contrast to the difficulty in forming a trapping layer of uniform thickness using conventional trapping layer forming devices for columnar honeycomb substrates 72 having a diameter of 180mm or more, a trapping layer of uniform thickness can be formed by using the particle attachment device 100 of the embodiment of the present invention.

Here, in the present specification, the term "diameter" refers to an equivalent circle diameter when the cross section of the columnar honeycomb substrate 72 is not circular.

The material constituting the columnar honeycomb substrate 72 is not particularly limited, and ceramic may be mentioned. Examples of the ceramics include cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composite materials (for example, si-bonded SiC), cordierite-silicon carbide composite materials, zirconia, spinel, indianite, sapphirine, corundum, titania, and silicon nitride. These ceramics may be used alone or in combination of 2 or more.

The end face shape of the columnar honeycomb substrate 72 is not particularly limited, and may be, for example, circular, elliptical, track-shaped, or oblong, or polygonal such as triangular or quadrangular. The illustrated columnar honeycomb substrate 72 is an example in the case where the end face shape is circular.

The shape of the cells in the cross section orthogonal to the direction in which the cells (the first cells 74 and the second cells 75) extend is not particularly limited, but is preferably quadrangular, hexagonal, octagonal, or a combination thereof. Among them, quadrangles (particularly squares) and hexagons are preferable. By forming the cell shape in this way, the pressure loss when the fluid is caused to flow in the columnar honeycomb filter can be reduced.

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

The thickness of the porous partition 77 is the length of a line segment crossing the partition when the centers of gravity of adjacent cells are connected to each other by the line segment in a cross section orthogonal to the direction in which the cells (the first cell 74 and the second cell 75) extend. The average thickness of the porous barrier ribs 77 is an average value of the thicknesses of all the porous barrier ribs 77.

The cell density (number of cells per unit cross-sectional area) of the columnar honeycomb substrate 72 is not particularly limited, and may be, for example, 6 to 2000 cells/square inch (0.9 to 311 cells/cm) ² ) Preferably 50 to 1000 cells/square inch (7.8 to 155 cells/cm) ² ) More preferably 100 to 400 cells/square inch (15.5 to 62.0 cells/cm) ² )。

The columnar honeycomb substrate 72 can be provided as an integrally molded product. The columnar honeycomb substrate 72 may be provided as a cell joined body in which a plurality of columnar honeycomb cells each having an outer peripheral wall are joined together on their side surfaces to be integrated. By providing the columnar honeycomb substrate 72 in the form of a cell assembly, thermal shock resistance can be improved.

The columnar honeycomb substrate 72 may be manufactured using methods well known in the art. The method of manufacturing the columnar honeycomb substrate 72 is exemplarily described below.

First, a raw material composition containing a ceramic raw material, a dispersion medium, a pore-forming material, and a binder is kneaded to form a green body, and then the green body is extruded to form a desired columnar honeycomb formed body. Additives such as dispersants may be blended as necessary in the raw material composition. In the extrusion molding, a die having a desired overall shape, cell shape, partition wall thickness, cell density, and the like may be used.

After drying the columnar honeycomb formed body, pore sealing parts are formed at prescribed positions on both end surfaces of the columnar honeycomb formed body, and then the pore sealing parts are dried to obtain the columnar honeycomb formed body with pore sealing parts. Thereafter, the columnar honeycomb formed body is degreased and fired to obtain a columnar honeycomb structure (columnar honeycomb base 72).

The ceramic raw material is a raw material which remains after firing and is a part of the ceramic constituting the skeleton of the columnar honeycomb structure. As the ceramic raw material, a raw material capable of forming the above ceramic after firing can be used. The ceramic raw material can be supplied in the form of powder, for example. Examples of the ceramic raw material include raw materials from which ceramics can be obtained, such as cordierite, mullite, zircon, aluminum titanate, silicon carbide, silicon nitride, zirconia, spinel, indian, sapphirine, corundum, and titania. Specific examples of such a raw material include, but are not limited to, silica, talc, alumina, kaolin, serpentine, pyrophyllite, brucite, boehmite, mullite, magnesite, aluminum hydroxide, and the like. The ceramic raw material may be used singly or in combination of 2 or more.

In the case where a columnar honeycomb filter is used for a DPF, a GPF, or the like, cordierite may be preferably used as the ceramic. In this case, as the ceramic raw material, a cordierite forming raw material can be used. The cordierite forming raw material is a raw material which is fired to form cordierite. The cordierite forming raw material preferably has alumina (Al ₂ O ₃ ) (containing the components of aluminium hydroxide converted to alumina): 30 to 45 mass% of magnesium oxide (MgO): 11 to 17 mass% of Silica (SiO) ₂ ): 42 to 57 mass% of chemical composition.

The dispersion medium may be water or a mixed solvent of water and an organic solvent such as alcohol, and water is particularly preferably used.

The pore-forming material is not particularly limited as long as it is a material that becomes pores after firing, and examples thereof include wheat flour, starch, foamed resin, water-absorbent resin, porous silica, carbon (for example, graphite), ceramic balls, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic acid, phenol, and the like. The pore-forming material may be used alone or in combination of 2 or more. From the viewpoint of improving the porosity of the fired body, the content of the pore-forming material is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more, relative to 100 parts by mass of the ceramic raw material. From the viewpoint of securing the strength of the fired body, the content of the pore-forming material is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and still more preferably 4 parts by mass or less, relative to 100 parts by mass of the ceramic raw material.

Examples of the binder include organic binders such as methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. In particular, methylcellulose and hydroxypropyl methylcellulose are preferably used in combination as the binder. From the viewpoint of improving the strength of the honeycomb formed body, the content of the binder is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 6 parts by mass or more, relative to 100 parts by mass of the ceramic raw material. From the viewpoint of suppressing occurrence of cracking due to abnormal heat generation in the firing step, the content of the binder is preferably 9 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of the ceramic raw material. The binder may be used alone or in combination of 2 or more.

As the dispersant, ethylene glycol, dextrin, fatty acid soap, polyether polyol, and the like can be used. The dispersant may be used alone or in combination of 2 or more. The content of the dispersant is preferably 0 to 2 parts by mass relative to 100 parts by mass of the ceramic raw material.

The method of sealing the end face of the columnar honeycomb formed body is not particularly limited, and a known method can be used. The material of the plugging portion 73 is not particularly limited, but ceramic is preferable from the viewpoints of strength and heat resistance. The ceramic is preferably a ceramic material containing at least 1 selected from cordierite, mullite, zircon, aluminum titanate, silicon carbide, silicon nitride, zirconia, spinel, indian, sapphirine, corundum, and titania. In order to make the expansion ratio at the time of firing the honeycomb body uniform and to improve durability, it is further preferable that the plugging portions 73 have the same material composition as the main body portion of the columnar honeycomb body.

After drying the honeycomb formed body, degreasing and firing are performed, whereby a columnar honeycomb structure (columnar honeycomb base 72) can be produced. The conditions of the drying step, degreasing step, and firing step may be any known conditions depending on the material composition of the honeycomb formed body, and specific conditions are not particularly described below.

In the drying step, 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 them, a drying method combining hot air drying and microwave drying or dielectric drying is preferable from the viewpoint of being capable of rapidly and uniformly drying the entire columnar honeycomb formed body.

In the case of forming the plugged portions, it is preferable that the plugged portions are formed at both end surfaces of the dried columnar honeycomb formed body, and then the plugged portions are dried. The hole sealing portions are formed at predetermined positions so that a plurality of first cells extending from the first end face to the second end face and having openings at the first end face and a plurality of second cells extending from the first end face to the second end face and having openings at the second end face are alternately arranged adjacent to each other with porous partition walls therebetween.

Next, a degreasing process will be described. The combustion temperature of the adhesive is about 200 ℃, and the combustion temperature of the pore-forming material is about 300-1000 ℃. Therefore, the degreasing step may be performed by heating the columnar honeycomb formed body to a temperature in the range of about 200 to 1000 ℃. The heating time is not particularly limited, and is usually about 10 to 100 hours. The columnar honeycomb formed body after the degreasing step is called a pre-fired body.

The firing step is also dependent on the material composition of the columnar honeycomb formed body, and can be performed by heating the calcined body to 1350 to 1600 ℃ and holding the calcined body for 3 to 10 hours, for example. In this way, a columnar honeycomb structure (columnar honeycomb substrate 72) having a plurality of first cells 74 and a plurality of second cells 75 can be produced, the first cells 74 extending from the first end face 71a to the second end face 71b, the first end face 71a being open and having plugged portions 73 at the second end face 71b, the second cells 75 extending from the first end face 71a to the second end face 71b, the second end face 71b being open and having plugged portions 73 at the first end face 71a, the first cells 74 and the second cells 75 being alternately arranged adjacent to each other with porous partition walls 77 interposed therebetween.

< retainer 10>

The holder 10 is a member that holds the filter base 70. The holder 10 is configured to be capable of holding the first end surface 71a of the filter base 70 in a position facing the nozzle 30 in a state where it is exposed. In one embodiment, the holder 10 may have a chuck mechanism 11 for holding the filter substrate 70 (e.g., the peripheral wall 76 of the columnar honeycomb substrate 72). The chuck mechanism 11 is not particularly limited, and a balloon chuck may be exemplified. The holder 10 has a case 12 for rectifying the aerosol passing through the filter substrate 70 in one direction without diffusing the aerosol.

As a material used for the holder 10, for example, metal or ceramic can be used. The metal may be stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, or the like. For reasons of high durability reliability, the material of the holder 10 is preferably stainless steel.

< Chamber 20>

The chamber 20 is a cylindrical member such as a cylinder or a square cylinder. The chamber 20 communicates with the holder 10, and is disposed such that the first end surface 71a of the filter substrate 70 faces the space in the chamber 20.

The chamber 20 has a side wall 22 connected to the holder 10 and a surface (facing surface 21) facing the first end surface 71a of the filter substrate 70. The facing surface 21 has an insertion opening for the nozzle 30. By adopting such a configuration, the aerosol ejected from the nozzle 30 can be directly introduced into the chamber 20.

As a material for the chamber 20, for example, metal, ceramic, or the like can be used. The metal may be stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, or the like. For reasons of high durability reliability, the material of the chamber 20 is preferably stainless steel.

An intake 40 that can take in ambient gas is provided on the opposing surface 21 of the chamber 20. By taking in ambient air from the intake port 40 provided in the opposed surface 21, the ambient air flows in the same direction as the flow direction of the aerosol sprayed from the nozzle 30, and therefore, the disturbance to the aerosol disappears, and the aerosol can be stabilized.

The shape of the inlet 40 is not particularly limited, and may be circular, elliptical, track-shaped, or oblong, or polygonal such as circular arc, triangle, or quadrangle.

The size and number of the intake ports 40 are not particularly limited as long as they are appropriately set according to the size of the facing surface 21.

As the facing surface 21, a perforated plate and/or a nonwoven fabric may be used in one embodiment. In order to prevent the agglomerated powder, the fragments of the filter base 70, dust, and the like from being taken in, a filter may be provided on the outer surface of the opposed surface 21.

In the case where the flow path cross-sectional area in the chamber 20 orthogonal to the flow direction of the aerosol is larger than the first end surface 71a of the filter substrate 70, the tapered portion 23 may be formed on the downstream side of the side wall 22 so that the flow path cross-sectional area gradually decreases toward the first end surface 71a of the filter substrate 70. The contour of the downstream-side end portion of the tapered portion 23 preferably matches the outer peripheral contour of the first end surface 71a of the filter base 70. With such a configuration, particles are easily supplied to the first end face 71a of the filter base 70.

The distance from the outlet of the nozzle 30 to the first end face 71a of the filter substrate 70 is preferably designed according to the area of the first end face 71a of the filter substrate 70. Specifically, since the aerosol is easily uniformly diffused in the direction orthogonal to the flow direction of the aerosol, it is preferable that the distance from the outlet of the nozzle 30 to the first end surface 71a of the filter substrate 70 becomes longer as the area of the first end surface 71a of the filter substrate 70 becomes larger. In one embodiment, the distance from the outlet of the nozzle 30 to the first end face 71a of the filter substrate 70 may be 500mm to 2000mm.

< nozzle 30>

The nozzle 30 is not particularly limited as long as it can spray the aerosol containing particles toward the first end surface 71a of the filter substrate 70.

The nozzle 30 is preferably provided at a position and orientation where aerosol can be injected in a direction orthogonal to the first end surface 71a of the filter base 70, and more preferably at a position and orientation where aerosol can be injected in a central portion of the first end surface 71a of the filter base 70.

In one embodiment, it is preferable that the nozzle 30 is provided in the center of the opposed surface 21, and a plurality of intake ports 40 are provided in the opposed surface 21 around the nozzle 30. By adopting such a structure, the effect of promoting the diffusion of particles in the aerosol mixed with the ambient gas in the chamber 20 can be improved.

< flow control Member 50>

The flow control member 50 is disposed on the opposing surface 21 (inner surface of the opposing surface 21) provided with the intake port 40, and is capable of controlling the flow of ambient gas.

The flow control member 50 is not particularly limited as long as it has a structure capable of controlling the flow of the ambient gas, but preferably has a plurality of blades 51 capable of controlling the flow of the ambient gas.

The inclination angle θ of the plurality of blades 51 with respect to the facing surface 21 is not particularly limited, but is preferably 80 ° or less, more preferably 70 ° or less, and still more preferably 60 ° or less. By controlling the inclination angle θ as described above, the swirling flow can be generated in the ambient gas and the aerosol injected from the nozzle 30 can be efficiently mixed, and therefore, the diffusion of particles in the aerosol mixed with the ambient gas can be promoted. On the other hand, if the inclination angle θ is too small, particles tend to adhere to the blade 51, and the material loss may increase. Therefore, the inclination angle θ is preferably 10 ° or more, more preferably 15 ° or more, and still more preferably 30 ° or more.

In the case where the plurality of blades 51 are provided on the opposed surface 21 provided with the intake port 40, only the plurality of blades 51 may be provided, but a member having the plurality of blades 51 may be provided from the viewpoint of ease of installation.

Here, fig. 4 shows a schematic top view of a component with a plurality of blades 51. Fig. 5 is a schematic enlarged cross-sectional view of the member in the circumferential direction (the facing surface 21 is also shown).

As shown in fig. 4 and 5, the member having the plurality of blades 51 preferably further includes a flat surface portion 52 parallel to the opposed surface 21 and a plurality of opening portions 53 provided on the flat surface portion 52 and exposing at least a part of the intake port 40, and the plurality of blades 51 are provided on the boundary between the flat surface portion 52 and the opening portions 53 and inclined toward the opening portions 53 side. The plurality of blades 51 preferably have substantially the same shape as the outer edge shape of the opening 53. In the case of such a member, the plate-like member can be easily manufactured by forming the cutouts in the opening 53 and the portions to be the plurality of blades 51 (excluding the boundary between the planar portion 52 and the opening 53) and then pushing out the portions where the cutouts are formed.

In one embodiment, the plurality of blades 51 may be provided in at least 2 rows in the radial direction from the center portion toward the outer peripheral portion of the facing surface 21. By adopting such a structure, the effect of generating the swirling flow of the surrounding gas can be improved.

As a material used for the flow control member 50, for example, metal, ceramic, or the like can be used. The metal may be stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, or the like. For reasons of high durability reliability, the material of the flow control member 50 is preferably stainless steel.

As shown in fig. 6, the particle attachment device 100 according to the embodiment of the present invention may further 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, and can be connected by a connection pipe 61, for example. By using the aerosol generator 60, the aerosol can be stably supplied to the nozzle 30.

The aerosol generator 60 is a device that ejects particles together with a fluid (driving gas). The type of the aerosol generator 60 is not particularly limited, and aerosol generators known in the art may be used. For example, the aerosol generator 60 having a mechanism for sucking particles by negative pressure generated by a high-speed fluid and discharging the particles together with the fluid can be used.

As the fluid (driving gas), the injection flow rate of the aerosol injected from the nozzle 30 can be controlled by using compressed gas such as compressed air with pressure adjusted. In addition, as the driving gas, dry air (for example, dew point of 10 ℃ or less) is preferably used in order to suppress aggregation of particles.

In the aerosol generator 60, in order to reduce abrasion due to contact with particles, a layer of a material composed of diamond, DLC (diamond-like carbon), titanium nitride (TiN), titanium carbonitride (TiCN), silicon carbonitride (SiCN), silicon carbide (SiC), silicon nitride (SiN), a superhard material, or an alloy or a combination thereof is preferably formed on the surface in contact with the particles. The layer may be formed by coating, plating, lining, or the like.

Here, fig. 7 shows a specific example of the aerosol generator 60.

The aerosol generator 420 shown in fig. 7 has:

a drive gas flow path 427 for flowing the pressurized drive gas;

a supply port 427i provided in the middle of the drive gas channel 427 and capable of sucking particles (e.g., ceramic particles 422) from the outer peripheral side of the drive gas channel 427 into the drive gas channel 427;

a nozzle 421 attached to the front end of the drive gas channel 427 and capable of ejecting aerosol;

a flow path 423 for sucking and transporting the ceramic particles 422, the flow path 423 having an outlet 423e communicating with the supply port 427 i; and

a housing part 429 for housing the ceramic particles 422 and supplying the ceramic particles 422 to the flow path 423 for suction conveyance.

For example, a funnel may be used as the receiving portion 429. The ceramic particles 422 adjusted to have a predetermined particle size distribution are accommodated in the accommodating portion 429. The ceramic particles 422 accommodated in the accommodating portion 429 receive the attractive force from the driving gas channel 427, are transported from the outlet 429e provided in the bottom of the accommodating portion 429 to the outlet 423e through the channel 423, and are introduced into the driving gas channel 427 from the supply port 427 i. At this time, the ambient gas (typically, air) sucked from the inlet 429i of the housing portion is also introduced into the driving gas channel 427 through the channel 423 together with the ceramic particles 422. The outlet 423e and the supply port 427i are common. The ceramic particles 422 are introduced into the driving gas channel 427 from a direction substantially perpendicular to the flow direction of the driving gas flowing through the driving gas channel 427.

The ceramic particles 422 supplied into the driving gas channel 427 collide with the driving gas flowing through the driving gas channel 427, are mixed while being broken up into aerosols, and are ejected from the nozzles 421. The nozzle 421 is preferably provided at a position and in an orientation where the aerosol can be injected in a direction perpendicular to the inlet side bottom surface of the columnar honeycomb structure. More preferably, the nozzle 421 is provided at a position and orientation where aerosol can be injected toward the center of the inlet-side bottom surface in a direction perpendicular to the inlet-side bottom surface.

The ceramic particles 422 are not limited to be supplied to the storage portion 429, and are preferably supplied by a powder quantitative feeder 4211 such as a screw feeder or a belt conveyor. The ceramic particles 422 discharged from the powder quantitative feeder 4211 can fall down into the housing part 429 by gravity.

In a preferred embodiment, the drive gas flow path 427 has a venturi portion 427v in which the flow path is narrowed, and the supply port 427i is provided downstream of a portion of the venturi portion 427v in which the flow path is most narrowed. If the driving gas flow path 427 has the venturi portion 427v, the velocity of the driving gas passing through the venturi portion 427v increases, and therefore, the higher velocity driving gas can collide with the ceramic particles 422 supplied downstream of the venturi portion 427v, and the crushing force increases. In order to increase the pulverizing force by the driving gas, it is more preferable that the supply port 427i is provided downstream of the portion where the flow path is most narrowed in the venturi portion 427v and adjacent to the portion. This structure can be achieved by, for example, connecting the drive gas flow path 427 and the flow path 423 for suction conveyance using the venturi jet 4210.

From the viewpoint of improving the breaking force of the ceramic particles, the lower limit of the flow rate of the driving gas immediately before passing through the venturi portion 427v is preferably 13m/s or more, more preferably 20m/s or more, and still more preferably 26m/s or more. The upper limit of the flow rate of the driving gas before passing through the venturi portion 427v is not particularly set, and is usually 50m/s or less, typically 40m/s or less.

From the viewpoint of improving the crushing force, the lower limit of the ratio of the flow path cross-sectional area immediately before the venturi portion 427v to the flow path cross-sectional area of the venturi portion 427v is preferably 8 or more, more preferably 16 or more. The upper limit of the ratio of the flow path cross-sectional area immediately before the venturi portion 427v to the flow path cross-sectional area of the venturi portion 427v is not particularly limited, but if it is excessively large, the pressure loss of the venturi portion 427v becomes large, and thus it is preferably 64 or less, more preferably 32 or less. Here, the flow path cross-sectional area of the venturi portion 427v means a flow path cross-sectional area of a portion of the venturi portion 427v where the flow path is narrowest. The flow path cross-sectional area immediately before the venturi portion 427v is the flow path cross-sectional area immediately before the upstream side flow path of the venturi portion 427v is narrowed.

When the venturi jet 4210 is used, for example, when the driving gas flows through the driving gas flow path 427, a large suction force can be applied to the flow path 423 for suction conveying, and the flow path 423 for suction conveying can be prevented from being blocked by the ceramic particles 422. The venturi jet 4210 is also effective as a removal means for the ceramic particles 422 when the flow path 423 for suction conveyance is blocked by the ceramic particles 42 b.

By using a compressed gas such as compressed air with a pressure adjusted as the driving gas, the ejection flow rate of the aerosol ejected from the nozzle 421 can be controlled. As the driving gas, dry air (for example, dew point of 10 ℃ or less) is preferably used for suppressing aggregation of the ceramic particles.

The fine ceramic particles 422 have a property of being easily aggregated. However, by using the aerosol generator 420 of the present embodiment, the ceramic particles 422 having a target particle size distribution, in which aggregation is suppressed, can be ejected.

As shown in fig. 8, the particle attaching device 100 according to the embodiment of the present invention may further include a blower 65 for imparting suction force to the second end surface 71b of the filter base 70. The blower 65 can be connected to the holder 10 via an exhaust pipe 66. By using the blower 65, the flow rate of the ambient gas flowing into the chamber 20 can be adjusted according to the suction force from the blower 65.

The blower 65 is a device having an exhaust function. The type of the blower 65 is not particularly limited, and a blower known in the art may be used.

A flow meter (not shown) may be provided in the exhaust pipe 66 to monitor the flow rate of the gas measured by the flow meter and to control the strength of the blower 65 according to the flow rate of the gas.

(2) Method for manufacturing filter

The method of manufacturing a filter according to the embodiment of the present invention is performed using the particle attaching device 100. The particle adhering device 100 can generate a swirling flow in the fluid in the chamber 20 by controlling the flow of the surrounding gas by the flow control member 50, and thus can promote the diffusion of particles in the fluid (aerosol) in the chamber 20. Therefore, by using the particle attachment device 100, a filter having a trapping layer with a uniform thickness can be manufactured.

In one embodiment, the method of manufacturing a filter according to the embodiment of the present invention includes a step of holding the filter substrate 70 in the holder 10 (hereinafter, referred to as a "holding step") and a step of injecting aerosol from the nozzle 30 toward the first end surface 71a of the filter substrate 70 while controlling the flow of ambient gas taken in from the intake port 40 provided in the opposing surface 21 of the chamber 20 by the flow control member 50, and causing particles to adhere to the filter substrate 70 (hereinafter, referred to as a "particle adhering step"). By performing such a process, the particle attachment device 100 can be appropriately controlled, and thus a filter having a trapping layer with a uniform thickness can be manufactured.

In the holding step, the first end surface 71a of the filter substrate 70 is disposed and held so as to face the space in the chamber 20. The holding method is not particularly limited as long as it is appropriately set according to the type of the holder 10.

In the particle adhering step, the flow of the surrounding gas can be controlled by the flow control member 50 to generate a swirling flow in the fluid in the chamber 20, so that when aerosol is injected from the nozzle 30 toward the first end face 71a of the filter substrate 70, the diffusion of particles can be promoted by the swirling flow of the surrounding gas. Therefore, the particles can be uniformly dispersed in the aerosol mixed with the surrounding gas before reaching the first end face 71a of the filter substrate 70. As a result, particles are uniformly supplied to the entire first end face 71a of the filter substrate 70 facing the space in the chamber 20, and a trapping layer of uniform thickness can be formed. For example, in the case where the filter substrate 70 is a columnar honeycomb substrate 72, particles are sucked into the first cells 74 open at the first end face 71a, and the particles sucked into the first cells 74 adhere to the surfaces of the first cells 74 to form a trapping layer.

In the particle adhering step, the average flow velocity of the aerosol flowing in the chamber 20 is preferably 0.5 to 3.0m/s, more preferably 1.0 to 2.0m/s, from the viewpoint of improving the film thickness stability of the particles adhering to the surface of the first cells 74.

In the particle adhering step, the lower limit of the average flow velocity of the aerosol flowing in the columnar honeycomb substrate 72 is preferably 0.5m/s or more, more preferably 1m/s or more, from the viewpoint of improving the film thickness stability of the particles adhering to the surface of the first cells 74. In order to maintain the high porosity of the porous barrier ribs 77, the upper limit of the average flow velocity of the aerosol flowing in the columnar honeycomb substrate 72 is preferably 20m/s or less, and more preferably 15m/s or less.

If the particle adhering process is continued, the pressure loss between the first end surface 71a and the second end surface 71b of the filter substrate 70 increases as the adhering amount of particles increases. Therefore, by obtaining the relationship between the amount of particles adhering to the pressure loss in advance, the end point of the particle adhering process can be determined based on the pressure loss. Accordingly, the particle attachment device 100 may be provided with a differential pressure gauge for measuring the pressure loss between the first end surface 71a and the second end surface 71b of the filter substrate 70, and may determine the end point of the particle attachment process based on the value of the differential pressure gauge.

In the case where the filter substrate 70 is a columnar honeycomb substrate 72, when the particle adhering step is performed, particles adhere to the first end face 71a of the columnar honeycomb substrate 72, and therefore, it is preferable to remove the particles by suction by vacuum or the like while flattening the first end face 71a by a jig such as a squeegee.

The particles contained in the aerosol are not particularly limited, and ceramic particles are preferable.

As the ceramic particles, the ceramic particles constituting the porous partition walls 77 are used. For example, ceramic particles containing 1 or 2 or more kinds selected from cordierite, silicon carbide (SiC), talc, mica, mullite, ceramic chips, aluminum titanate, alumina, silicon nitride, siAlON (SiAlON), zirconium phosphate, zirconium oxide, titanium oxide, and silicon dioxide may be used. The ceramic particles preferably have silicon carbide, alumina, silica, cordierite or mullite as the main component. The main component of the ceramic particles is a component that accounts for 50 mass% or more of the ceramic particles. The ceramic particles preferably account for 50 mass% or more of SiC, more preferably 70 mass% or more, and still more preferably 90 mass% or more.

After the particle adhering step, the filter substrate 70 on which particles are adhered is subjected to a heat treatment at a maximum temperature of 1000 ℃ or higher for 1 hour or more, for example, 1 hour to 6 hours, typically at a maximum temperature of 1100 ℃ to 1400 ℃ for 1 hour to 6 hours, thereby completing the filter. The heat treatment may be performed by placing the filter substrate 70 with particles attached thereto in an electric furnace or a gas furnace, for example. By the heat treatment, the particles are bonded to each other, and the particles burn to adhere to the filter substrate 70, forming a trapping layer. When the heat treatment is performed under oxygen-containing conditions such as air, oxide films are formed on the surfaces of the particles, and the bonding of the particles to each other is promoted. This can provide a trapping layer that is difficult to separate from the filter substrate 70.

(3) Filter with honeycomb structure

Fig. 9 is a schematic cross-sectional view (cross-sectional view parallel to the direction in which cells extend) of a columnar honeycomb filter according to an embodiment of the present invention. Fig. 10 is a schematic end view of the columnar honeycomb filter (end view of the first end face).

As shown in fig. 9 and 10, the columnar honeycomb structure filter 200 according to the embodiment of the present invention includes a columnar honeycomb substrate 72 and a trapping layer 80, wherein the columnar honeycomb substrate 72 includes a plurality of first cells 74 extending from the first end face 71a to the second end face 71b and having the plugged portions 73 in the second end face 71b while opening the first end face 71a, and a plurality of second cells 75 extending from the first end face 71a to the second end face 71b and having the plugged portions 73 in the first end face 71b while opening the second end face 71b, and the first cells 74 and the second cells 75 are alternately arranged adjacent to each other with the porous partition walls 77 therebetween; the trapping layer 80 is formed on the surface of the first cells 74. In fig. 9 and 10, the example in which the trapping layer 80 is formed on the surface of the first cell 74 is shown, but the trapping layer 80 may be formed on the surface of the second cell 75 or on the surfaces of both the first cell 74 and the second cell 75.

The difference in thickness of the trapping layer 80 of the columnar honeycomb filter 200 according to the embodiment of the present invention is 15 μm or less, preferably 13 μm or less. If the difference is within this range, the trapping layer 80 can be made to have a uniform thickness, and therefore the trapping effect of the Particulate Matter (PM) can be improved.

The thickness of the trapping layer 80 is likely to be different in the cross section of the columnar honeycomb filter 200 perpendicular to the direction in which the first cells 74 and the second cells 75 extend, particularly between the central portion and the outer peripheral portion. Therefore, the difference in thickness of the trapping layer 80 is preferably calculated by obtaining the difference between the thickness of the center portion and the thickness of the outer peripheral portion in this cross section. Here, the center portion refers to a portion located at a distance of 1/3 of the diameter (distance from the center to the outer periphery) from the center in the cross section, and the outer periphery portion refers to a portion located at a distance of 1/3 of the diameter from the outer periphery.

The thickness of the trapping layer 80 can be measured by using a 3-dimensional measuring machine (model VR-3200 or VR-5200) manufactured by KEYENCE, inc. The measurement may be performed at a position 25mm in the direction in which the cells (first cells 74 and second cells 75) extend from the end surfaces (first end surface 71a and second end surface 71 b).

In the columnar honeycomb filter 200 according to the embodiment of the present invention, when exhaust gas containing Particulate Matter (PM) such as soot is supplied to the first end face 71a of the columnar honeycomb filter 200, the exhaust gas is introduced into the first cells 74 and proceeds downstream in the first cells 74. Since the first cells 74 have the hole-sealing portions 73 on the downstream second end face 71b, the exhaust gas flows into the second cells 75 through the porous partition walls 77 that divide the first cells 74 and the second cells 75 and form the trapping layer 80. The particulate matter cannot pass through the porous partition 77 formed with the trapping layer 80, and is thus trapped and accumulated in the first cells 74. After the particulate matter is removed, the clean exhaust gas flowing into the second cells 75 advances downstream in the second cells 75, and flows out from the downstream second end face 71 b.

The columnar honeycomb filter 200 according to the embodiment of the present invention preferably has a diameter of 180mm or more in a cross section orthogonal to the direction in which the first cells 74 and the second cells 75 extend. In contrast to the conventional particle attachment device in which it is difficult to form the trapping layer 80 having a uniform thickness on the columnar honeycomb substrate 72 having a diameter of 180mm or more, the particle attachment device 100 according to the embodiment of the present invention can form the trapping layer 80 having a uniform thickness on the columnar honeycomb substrate 72 having a diameter of 180mm or more.

The columnar honeycomb structure filter 200 according to the embodiment of the present invention can be manufactured by using the columnar honeycomb substrate 72 as the filter substrate 70 and according to the above-described method for manufacturing a filter.

Examples

The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(A) Manufacture of columnar honeycomb substrates

To 100 parts by mass of the cordierite forming raw material, 3 parts by mass of the pore-forming material, 55 parts by mass of the dispersion medium, 6 parts by mass of the organic binder, and 1 part by mass of the dispersant were added, followed by mixing and kneading to prepare a green clay. As cordierite forming raw materials, alumina, aluminum hydroxide, kaolin, talc and silica are used. Water is used as a dispersion medium, a water-absorbent polymer is used as a pore-forming material, hydroxypropyl methylcellulose is used as an organic binder, and a fatty acid soap is used as a dispersing agent.

The green clay was put into an extrusion molding machine, and extrusion was performed through a die of a predetermined shape, whereby a cylindrical honeycomb molded body was obtained. The obtained honeycomb formed body was subjected to dielectric drying and hot air drying, and then both end surfaces were cut so as to have a predetermined size, thereby obtaining a honeycomb dried body.

The obtained honeycomb dried body was subjected to pore sealing by alternately disposing the first cells and the second cells, and then subjected to thermal degreasing at about 200 ℃ in an atmosphere, and further subjected to firing at 1420 ℃ for 5 hours in an atmosphere, to obtain a columnar honeycomb substrate.

The specifications of the columnar honeycomb substrate are as follows.

Overall shape: cylindrical with diameter 270mm x height 300mm

Cell shape in cross section orthogonal to the direction in which the cells extend: square shape

Cell density (number of cells per unit cross-sectional area): 200 cells/square inch (31.1 cells/cm) ² )

Thickness of porous partition wall: 0.2mm (nominal value based on the specification of the die)

(B) Manufacture of columnar honeycomb filter

As for the columnar honeycomb substrate, the particle adhering device having the structure shown in fig. 8 was used, and the flow of the ambient gas taken in from the intake port provided on the opposite surface of the chamber was controlled by the flow control member, while aerosol containing ceramic particles was sprayed from the nozzle toward the first end surface of the columnar honeycomb substrate, and the ceramic particles were adhered to the surface of the first cells of the columnar honeycomb substrate.

The specification and operating conditions of the particle attachment apparatus are as follows.

< flow control Member >

The structure is as follows: the flow control member having the structure shown in fig. 4 (2 rows of blades are provided in the radial direction from the center portion of the facing surface toward the outer peripheral portion)

Inclination angle θ of the blade with respect to the opposing surface: 15 to 60 ° (specific inclination angle θ in each example is shown in table 1. It is to be noted that in comparative example 1, no flow control member is used.)

< Chamber >

Shape: cylindrical shape

Inner diameter: 300mm

Length: 850mm

Ambient gas: air-conditioner

The structure of the opposite surface: punching plate

Filter arrangement at the intake: has the following components

Position of the nozzle: central portion of the opposed surface

Distance from the outlet of the nozzle to the first end face of the columnar honeycomb substrate: 850mm

< Aerosol Generator >

Product name: none (manufactured by this company) (having the structure shown in FIG. 7)

Category: continuous aerosol generator

Drive gas flow path and connection method of flow path for suction transport: venturi ejector

The installation position of the ceramic particle supply port: a position downstream of a portion where the flow path is the smallest in the venturi portion and adjacent to the portion

A method for supplying ceramic particles to a storage section: screw feeder

The type of the housing part: funnel(s)

The type of ceramic particles contained in the containing section: siC particles

Volume-based particle size distribution of ceramic particles (measured by laser diffraction/scattering): median particle diameter (D50) =3μm, siC particles having a particle size of 10 μm or more: less than or equal to 20 percent by volume

Driving gas: compressed dry air (dew point below 10℃)

The sucked ambient gas: air-conditioner

Average flow rate of ambient gas flowing in a flow path for suction transport: the concentration of the solution is 40L/min,

average flow rate of the driving gas flowing in the driving gas flow path before converging with the sucked ambient gas: 80L/min

Ratio of flow path cross-sectional area immediately before venturi portion to flow path cross-sectional area of venturi portion = 1:0.028

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

Average flow of aerosol ejected from nozzle: 120L/min (measured by a flowmeter)

Mass flow of ceramic particles in aerosol ejected from nozzle: 0.5g/s (measured by a flowmeter)

< operating conditions >

Intake flow of blower: 4000L/min

Average flow rate of aerosol flowing within the columnar honeycomb substrate: about 10m/s (calculated by flow/cell opening area)

End point of the ceramic particle adhesion process: the time when the differential pressure gauge reaches +0.1kPa to +0.4kPa (the differential pressure value varies due to the difference in membrane mass set according to the product volume)

Next, the ceramic particles adhering to the first end face of the columnar honeycomb substrate obtained in this way were removed by vacuum suction while the first end face was flattened by a squeegee. Then, the columnar honeycomb substrate was placed in an electric furnace, and heat treatment was performed under an atmospheric atmosphere at a maximum temperature of 1200 ℃ for 2 hours, thereby obtaining a columnar honeycomb filter having a trapping layer formed on the surface of the first cell.

The thickness of the trapping layer in the central portion and the peripheral portion of the columnar honeycomb filter obtained as described above was determined by using a 3-dimensional measuring machine (model VR-3200 or VR-5200) manufactured by KEYENCE, inc. At a position 25mm in the direction extending from the first end face in the first cell.

In the above-described production of the columnar honeycomb filter, the raw material loss in the ceramic particle adhesion step was calculated. The raw material loss was calculated by subtracting the amount of ceramic particles adhering to the columnar honeycomb substrate from the amount of ceramic particles supplied for the formation of the trapping layer. The amount of ceramic particles to be supplied for forming the trapping layer is the amount of ceramic particles supplied in the screw feeder. The amount of ceramic particles attached to the columnar honeycomb substrate was calculated from the difference in mass of the columnar honeycomb substrate before and after the formation of the trapping layer.

The evaluation results are shown in table 1.

TABLE 1

As shown in table 1, the difference in thickness between the center portion and the outer peripheral portion of the trapping layer formed using the particle attachment device having no flow control member was large (comparative example 1), while the difference in thickness between the center portion and the outer peripheral portion of the trapping layer formed using the particle attachment device having the flow control member was small (examples 1 to 4). In addition, the smaller the inclination angle θ of the blade of the flow control member, the more likely ceramic particles adhere to the blade, and thus the raw material loss tends to increase.

As is clear from the above results, according to the present invention, it is possible to provide a particle attaching device and a method for manufacturing a filter, which can form a trapping layer of uniform thickness without being affected by the type and size of a filter base material. In addition, according to the present invention, a columnar honeycomb structure filter having a trapping layer of uniform thickness can be provided.

Symbol description

10: retainer, 20: chamber, 21: opposing faces, 22: side wall, 23: taper portion, 30: nozzle, 40: inlet, 50: flow control member, 51: blade, 52: plane portion, 53: opening portion, 60: aerosol generator, 61: connecting pipe, 65: blower, 66: exhaust pipe, 70: filter base material, 71a: first end face, 71b: second end face, 72: columnar honeycomb substrate, 73: hole sealing portion, 74: first cell, 75: second cells, 76: peripheral wall, 77: porous partition wall, 80: trapping layer, 100: particle attachment device, 200: columnar honeycomb filter, 420: aerosol generator, 421: nozzle, 422: ceramic particles, 423: flow path, 423e: outlet, 427: drive gas flow path, 427i: supply port, 427v: venturi portion, 429: receiving portion 429i: inlet, 429e: outlet, 4210: venturi injector, 4211: a powder quantitative feeder.

Claims (15)

1. A particle attaching device is provided with:

a holder for holding a filter substrate having a first end face into which a fluid can flow and a second end face from which the fluid can flow,

a chamber in communication with the holder, the chamber being disposed with the first end face of the filter substrate facing a space within the chamber,

a nozzle disposed on an opposite surface of the chamber opposite to the first end surface of the filter substrate, the nozzle being capable of ejecting an aerosol containing particles toward the first end surface of the filter substrate,

an intake port provided on the opposing surface of the chamber and capable of taking in ambient gas, and

and a flow control member which is disposed on the facing surface provided with the intake port and is capable of controlling the flow of the ambient gas.

2. The particle attachment device of claim 1, wherein,

the flow control member has a plurality of blades having an inclination angle of 10 to 80 ° with respect to the opposing surface.

3. The particle attachment device of claim 2, wherein,

the flow control member further has a planar portion parallel to the opposed surface and a plurality of openings provided in the planar portion and exposing at least a part of the intake port,

The blade is provided at a boundary between the planar portion and the opening portion and is inclined toward the opening portion side.

4. The particle attachment device of claim 3, wherein,

the blade has a shape substantially identical to the outer edge shape of the opening.

5. The particle attachment device according to any one of claims 2 to 4, wherein,

the blades are provided in at least 2 rows in a radial direction from a central portion of the opposed surface toward an outer peripheral portion.

6. The particle attachment device according to any one of claims 1 to 5, wherein,

the nozzle is provided in a central portion of the opposed surface, and the intake port is provided in plurality on the opposed surface around the nozzle.

7. The particle attachment device according to any one of claims 1 to 6, wherein,

the filter substrate is a columnar honeycomb substrate having a plurality of first cells extending from the first end face to the second end face and having openings at the first end face and having plugged portions at the second end face, and a plurality of second cells extending from the first end face to the second end face and having openings at the first end face and having plugged portions at the first end face, the first cells and the second cells being alternately arranged adjacent to each other with porous partition walls therebetween.

8. The particle attachment device of claim 7, wherein,

the columnar honeycomb substrate has a diameter of 180mm or more in a cross section orthogonal to a direction in which the first cells and the second cells extend.

9. The particle attachment device according to any one of claims 1 to 8, wherein,

the particle attachment device further comprises an aerosol generator connected to the nozzle.

10. The particle attachment device according to any one of claims 1 to 9, wherein,

the particle attachment device further includes a blower for imparting an attractive force to the second end surface of the filter base material.

11. A method for manufacturing a filter, wherein,

use of the particle attachment device according to any one of claims 1 to 10.

12. The method of manufacturing a filter according to claim 11, comprising:

a step of holding the filter base material in the holder, and

and a step of spraying the aerosol from the nozzle toward the first end surface of the filter substrate while controlling the flow of the ambient gas taken in from the inlet provided on the opposed surface of the chamber by the flow control member, thereby adhering the particles to the filter substrate.

13. The method for manufacturing a filter according to claim 11 or 12, wherein,

the particles are ceramic particles.

14. The method for manufacturing a filter according to claim 13, wherein,

the ceramic particles comprise silicon carbide, alumina, silicon dioxide, cordierite or mullite as main components.

15. A columnar honeycomb filter, comprising:

a columnar honeycomb substrate having a plurality of first cells extending from a first end face to a second end face and having openings in the first end face and having plugged portions in the second end face, and a plurality of second cells extending from the first end face to the second end face and having openings in the second end face and having plugged portions in the first end face, the first cells and the second cells being alternately arranged adjacent to each other with porous partition walls interposed therebetween, and

a trapping layer formed on a surface of at least one of the first cells and the second cells;

wherein the difference in thickness of the trapping layer is 15 μm or less.

Images