Inspection apparatus and methods for columnar honeycomb filters

Abstract

The inspection device (100) for the columnar honeycomb filter (1) includes: a receiving section (10) for receiving the columnar honeycomb filter (1); an inlet pipe (20) and an outlet pipe (30) for gas flow and connected to the receiving section (10); a particle generating section (40) for generating particles; a particle introducing section (50) for introducing particles generated by the particle generating section (40) into the inlet pipe (20); a gas stirring section (60) provided on the upstream side of the inlet pipe (20) in the gas flow direction (X); and a particle counter (70a, 70b) provided on the downstream side of the inlet pipe (20) and the outlet pipe (30) in the gas flow direction (X) for counting the number of particles.

Description

TECHNICAL FIELD

[0001] The present application relates to an inspection device and an inspection method for a columnar honeycomb filter. BACKGROUND

[0002] In exhaust gas discharged from an internal combustion engine such as a diesel engine and a gasoline engine, particulate matter (hereinafter, referred to as PM) such as soot is contained. PM such as soot is harmful to the human body, and the discharge is regulated. Currently, in order to cope with the exhaust gas regulation, filters typified by a diesel particulate filter (DPF) and a gasoline particulate filter (GPF) that filter PM such as soot by passing exhaust gas through small-pored partition walls having gas permeability are widely used.

[0003] As a filter for trapping PM such as soot, a wall-flow type columnar honeycomb structure (hereinafter, also referred to as "columnar honeycomb filter") is known, which has partition walls that divide a plurality of first cells extending from a first end face to a second end face and second cells, the first cells and the second cells are arranged adjacent to each other with the partition walls, the first end face of the first cell and the second end face of the second cell are open, and a plugged portion is provided at the second end face of the first cell and the first end face of the second cell.

[0004] In recent years, as the exhaust gas regulation is strengthened, a more stringent PM discharge standard (PN limit: Particle Matter Number limit) is introduced, and for filters, it is required to improve the inspection accuracy of the PM trapping performance (PN trapping efficiency).

[0005] As a conventional inspection method, a method is known in which soot particles having a median particle diameter of 300 nm are supplied to a filter, the number of soot particles before and after the supply to the filter is measured with a particle counter, and the difference is calculated (Patent Literature 1). In addition, a method is known in which a gas containing fine particles is supplied to the first end face of a columnar honeycomb filter, and a sheet-shaped light parallel to the second end face is irradiated in a manner of covering the entire second end face, and the entire second end face is photographed using a camera (Patent Literature 2).

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: U.S. Patent Application Publication No. 2020 / 0254435 Specification

[0009] Patent Literature 2: Japanese Patent No. 6756939 SUMMARY

[0010] (PROBLEMS TO BE SOLVED BY THE INVENTION)

[0011] In the inspection method of Patent Document 1, the supply amount of soot particles is prone to variation depending on their position within the filter. This is because, in the inspection method of Patent Document 1, the soot particles are difficult to agitate, resulting in uneven concentration distribution of soot particles in a plane orthogonal to the supply direction. Therefore, even when inspecting the same product, the measured values ​​will deviate depending on the orientation or installation method of the filter, thus reducing the accuracy of the collection performance inspection.

[0012] Furthermore, the inspection method in Patent Document 2 is based on simply evaluating the difference in brightness on an image by considering the scattering of light when a sheet of light is irradiated by microparticles. Therefore, the inspection accuracy of the capture performance cannot be said to be sufficient.

[0013] The present invention was made to solve the aforementioned problems, and its purpose is to provide an inspection device and method for columnar honeycomb filters with high accuracy in inspecting their trapping performance.

[0014] (Methods used to solve problems)

[0015] The inventors discovered that by setting a gas stirring section at a given position in the inspection device of a columnar honeycomb filter, the particles are effectively stirred to suppress the uneven distribution of soot particles in a plane perpendicular to the gas flow direction X, thereby improving the inspection accuracy of the collection performance, thus completing the present invention.

[0016] That is, the present invention is an inspection device for a columnar honeycomb filter, comprising:

[0017] The containment section is capable of housing a columnar honeycomb filter;

[0018] The inlet pipe and outlet pipe allow gas to flow and are connected to the receiving part;

[0019] The particle generation unit produces particles;

[0020] The particle introduction section introduces the particles generated by the particle generation section into the introduction tube;

[0021] A gas stirring section, and an inlet pipe disposed upstream of the particle inlet section in the direction of gas flow; and

[0022] A particle counter is provided in the inlet pipe and the outlet pipe, which are located downstream of the particle inlet in the direction of gas flow, to measure the number of particles.

[0023] Furthermore, the present invention provides a method for inspecting a columnar honeycomb filter, comprising:

[0024] The particle generation process produces particles;

[0025] The particle introduction process involves introducing the particles generated in the particle generation process into the gas stirred by the gas stirring unit.

[0026] The particle supply process involves supplying the gas containing the particles to a columnar honeycomb filter; and

[0027] The particle counting process measures the number of particles in the gas upstream and downstream of the columnar honeycomb filter in the direction of gas flow.

[0028] (Invention Effects)

[0029] According to the present invention, an inspection apparatus and method for columnar honeycomb filters with high accuracy in inspecting their trapping performance can be provided. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an inspection device for a columnar honeycomb filter according to an embodiment of the present invention.

[0031] Figure 2 This is a cross-sectional view of the columnar honeycomb filter used in the inspection device for the columnar honeycomb filter according to an embodiment of the present invention.

[0032] Figure 3 yes Figure 2 End face view of a columnar honeycomb filter.

[0033] Figure 4 yes Figure 1 A magnified view of the area surrounding the particle introduction section.

[0034] Figure 5 This is a top view of the gas stirring plate used in the inspection device for the columnar honeycomb filter according to an embodiment of the present invention.

[0035] Figure 6 yes Figure 5 A cross-sectional view of the gas stirring plate along line a-a'.

[0036] Figure 7 This is a schematic diagram of an inspection device for another columnar honeycomb filter according to an embodiment of the present invention. Detailed Implementation

[0037] 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 changes or improvements can be made to the following embodiments based on the ordinary knowledge of those skilled in the art, and the resulting solutions are also included in the scope of the present invention.

[0038] (1) Inspection device for columnar honeycomb filters

[0039] Figure 1 This is a schematic diagram of an inspection device for a columnar honeycomb filter according to an embodiment of the present invention.

[0040] like Figure 1 As shown, the inspection device 100 for a columnar honeycomb filter includes: a housing 10 for housing the columnar honeycomb filter; an inlet pipe 20 and an outlet pipe 30 for gas flow and connected to the housing 10; a particle generating unit 40 for generating particles; a particle introducing unit 50 for introducing particles generated by the particle generating unit 40 into the inlet pipe 20; a gas stirring unit 60 disposed upstream of the inlet pipe 20 in the gas flow direction X; and particle counters 70a and 70b disposed downstream of the inlet pipe 20 and outlet pipe 30 in the gas flow direction X to count the number of particles. With this structure, particles can easily diffuse into the gas, thus suppressing uneven particle concentration distribution in a plane perpendicular to the gas flow direction X. Furthermore, since the particle counters 70a and 70b count the number of particles with this suppressed uneven concentration distribution, the inspection accuracy of the collection performance can be improved.

[0041] In addition, Figure 1 The image shows an example of a horizontal arrangement of components such as the inlet pipe 20 and the outlet pipe 30, but it should be noted that these components can also be arranged vertically.

[0042] The columnar honeycomb filter to be inspected and the components of the inspection device 100 for the columnar honeycomb filter will be described in detail below.

[0043] <Columnar honeycomb filter>

[0044] The columnar honeycomb filter used in the inspection device 100 is a wall-flow columnar honeycomb structure. The columnar honeycomb filter can be used as a DPF and GPF for collecting particulate matter (PM) such as soot from combustion devices, typically installed in the exhaust pipes of a vehicle's engine.

[0045] Figure 2 And 3 is a schematic cross-sectional view (a cross-sectional view parallel to the direction of the compartment extension) and an end view (an end view of the first end face) of the columnar honeycomb filter.

[0046] like Figure 2 as well as Figure 3As shown, the columnar honeycomb filter 1 includes: an outer peripheral wall 2; a plurality of first compartments 4a disposed on the inner side of the outer peripheral wall 2, extending from a first end face 3a to a second end face 3b, the first end face 3a being open and a sealing portion 6 being provided on the second end face 3b; a plurality of second compartments 4b disposed on the inner side of the outer peripheral wall 2, extending from the first end face 3a to the second end face 3b, the first end face 3a being provided with a sealing portion 6 and the second end face 3b being open; and a porous partition wall 5 dividing to form the first compartments 4a and the second compartments 4b. The first compartments 4a and the second compartments 4b are alternately arranged adjacent to each other with respect to the partition wall 5, thereby the first end face 3a and the second end face 3b are respectively honeycomb-shaped.

[0047] When exhaust gas containing particulate matter (PM) such as soot is supplied to the first end face 3a on the upstream side of the columnar honeycomb filter 1, the exhaust gas is introduced into the first compartment 4a and proceeds downstream within the first compartment 4a. Since the first compartment 4a has a sealing portion 6 on the second end face 3b on the downstream side, the exhaust gas flows into the second compartment 4b through the porous partition 5 that divides the first compartment 4a and the second compartment 4b. PM cannot pass through the partition 5 and is therefore captured and deposited in the first compartment 4a. After the PM is removed, the clean exhaust gas flowing into the second compartment 4b proceeds downstream within the second compartment 4b and exits from the second end face 3b on the downstream side.

[0048] There are no particular limitations on the materials used to constitute the columnar honeycomb filter 1, but porous ceramics can be cited as examples. Examples of ceramics include cordierite, andalusite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indian quartz, pseudosapphire, corundum, titanium dioxide, and silicon nitride. These ceramics can be used alone or in combination of two or more.

[0049] The columnar honeycomb filter 1 may also have a catalyst, such as one that assists in the combustion of PM, supported on the surface of the partition 5 or inside it. Examples of catalysts include, for example, noble metals (Pt, Pd, Rh, etc.), alkali metals (Li, Na, K, Cs, etc.), alkaline earth metals (Ca, Ba, Sr, etc.), rare earth elements (Ce, Sm, Gd, Nd, Y, Zr, Ca, La, Pr, etc.), and transition metals (Mn, Fe, Co, Ni, Cu, Zn, Sc, Ti, V, Cr, etc.).

[0050] The end face shape of the columnar honeycomb filter 1 is not particularly limited, but it can be, for example, a circular, elliptical, racetrack-shaped, or oblong arc shape, or a polygonal shape such as a triangle or quadrilateral. Furthermore, the illustrated columnar honeycomb filter 1 is an example of a filter with a circular end face and a cylindrical outer shape.

[0051] The shape of the compartments in a cross-section perpendicular to the flow direction of the compartments (first compartment 4a and second compartment 4b) is not particularly limited, but is preferably quadrilateral, hexagonal, octagonal, or a combination thereof. Among these, square and hexagonal shapes are preferred. By forming the compartment shape in this way, the pressure loss when the fluid flows through the columnar honeycomb filter 1 can be reduced.

[0052] There are no specific limitations on the compartment density (the number of compartments per unit cross-sectional area), for example, it can be set to 6 to 2000 compartments / square inch (0.9 to 311 compartments / cm²). 2 More preferably, it is 50–1000 compartments / square inch (7.8–155 compartments / cm²). 2 ), particularly preferred is 100–400 compartments / square inch (15.5–62.0 compartments / cm²). 2 ).

[0053] The columnar honeycomb filter 1 can also be provided as a one-piece molded product. Furthermore, the columnar honeycomb filter 1 can also be provided as a unit assembly in which multiple columnar honeycomb units, each having an outer peripheral wall 2, are joined together on their sides. By providing the columnar honeycomb filter 1 as a unit assembly, thermal shock resistance can be improved.

[0054] The columnar honeycomb filter 1 can be manufactured using methods known in the art. The method for manufacturing the columnar honeycomb filter 1 will be described illustratively below.

[0055] First, a raw material composition containing ceramic raw materials, a dispersion medium, a pore-forming material, and a binder is kneaded 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, compartment shape, compartment wall thickness, and compartment density can be used.

[0056] After drying the columnar honeycomb molded body, sealing portions are formed on both ends of the columnar honeycomb molded body, and then the sealing portions are dried to obtain a columnar honeycomb molded body with sealing portions. Then, the columnar honeycomb filter 1 is manufactured by degreasing and firing the columnar honeycomb molded body.

[0057] As ceramic raw materials, any raw material capable of forming the aforementioned ceramic after firing can be used. Ceramic raw materials can be provided, for example, in powder form. Examples of ceramic raw materials include cordierite, andalusite, zircon, aluminum titanate, silicon carbide, silicon nitride, zirconium oxide, spinel, Indian stone, pseudosapphire, corundum, and titanium dioxide. More specifically, without limitation, examples include silicon dioxide, talc, alumina, kaolin, serpentine, pyrophyllite, brucite, boehmite, andalusite, magnesite, and aluminum hydroxide. Ceramic raw materials can be used alone or in combination of two or more.

[0058] In applications such as DPF and GPF filters, cordierite is preferably used as the ceramic. In this case, cordierite-modified raw materials can be used as the ceramic raw materials. Cordierite-modified raw materials are raw materials that are converted into cordierite through firing. The cordierite-modified raw materials preferably consist of the following chemical composition: alumina (Al2O3) (including the amount of aluminum hydroxide converted into alumina): 30-45% by mass, magnesium oxide (MgO): 11-17% by mass, and silicon dioxide (SiO2): 42-57% by mass.

[0059] Examples of dispersion media include water or mixtures of water and organic solvents such as alcohols, but water is particularly preferred.

[0060] 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, propylene, phenol, etc. The pore-forming material can be used alone or in combination of two or more. 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.

[0061] Examples of adhesives include organic adhesives such as methylcellulose, hydroxypropyl methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. It is preferable to use both methylcellulose and hydroxypropyl methylcellulose simultaneously. 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. The adhesive can be used alone or in combination of two or more types.

[0062] Dispersants such as ethylene glycol, dextrin, fatty acid soaps, and polyether polyols can be used. Dispersants can be used alone or in combination of two or more. The preferred content of the dispersant is 0 to 2 parts by weight relative to 100 parts by weight of the ceramic raw material.

[0063] There are no particular limitations on the method for sealing the end faces of the columnar honeycomb molded body; known methods can be used. There are no particular limitations on the material of the sealing portion 6, but ceramic is preferred from the viewpoint of strength and heat resistance. As ceramic, it is preferred to contain at least one material selected from the group consisting of cordierite, andalusite, zircon, aluminum titanate, silicon carbide, silicon nitride, zirconium oxide, spinel, indigo, pseudosapphire, corundum, and titanium dioxide. In order to ensure a uniform expansion rate during firing and improve durability, the sealing portion 6 is more preferably made of the same material as the main body of the honeycomb molded body.

[0064] After drying the honeycomb molded body, degreasing and firing are performed to manufacture columnar honeycomb filter 1. The conditions for the drying, degreasing and firing processes can be well-known conditions based on the material composition of the honeycomb molded body. Although no special explanation is required, examples of specific conditions are listed below.

[0065] In the drying process, existing and 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, a drying method combining hot air drying with microwave drying or dielectric drying is preferred for the purpose of rapidly and uniformly drying the entire molded body. In the case of forming sealing portions, it is preferable to dry the sealing portions after they have been formed on both end faces of the dried honeycomb molded body.

[0066] The degreasing process will be explained next. The burning temperature of the adhesive is around 200℃, and the burning temperature of the pore-forming material is around 300-1000℃. Therefore, the degreasing process only requires heating the honeycomb molded body to a temperature range of around 200-1000℃. There is no particular limit to the heating time, which is usually around 10-100 hours. The honeycomb molded body after the degreasing process is called the pre-fired body.

[0067] The firing process also depends on the material composition of the 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.

[0068] The sintered honeycomb structure can be used directly as a filter, but to improve PM collection efficiency, a porous membrane for PM collection can also be formed separately on the partition 5. The porous membrane can be formed using any known method. In one embodiment, the porous membrane may contain a total of 50% by mass or more of one or more selected from silicon carbide, cordierite, alumina, silica, andalusite, and aluminum titanate.

[0069] <Containment Department 10>

[0070] The housing 10 is a component capable of housing the columnar honeycomb filter 1.

[0071] The shape of the receiving part 10 is not particularly limited and can be appropriately set according to the shape of the columnar honeycomb filter 1. For example, if the columnar honeycomb filter 1 is cylindrical, the receiving part 10 can be cylindrical.

[0072] In the housing section 10, the columnar honeycomb filter 1 is housed with its first end face 3a facing the inlet pipe 20 and its second end face 3b facing the outlet pipe 30.

[0073] For example, metals or ceramics can be used as materials for the housing section 10. Examples of metals include stainless steel, titanium alloys, copper alloys, aluminum alloys, and brass. Stainless steel is preferred as the material for the housing section 10 due to its high durability and reliability.

[0074] <Inlet tube 20 and outlet tube 30>

[0075] The inlet pipe 20 and the outlet pipe 30 are components that allow gas to flow and are connected to the housing 10. The inlet pipe 20 is located upstream of the housing 10 in the gas flow direction X. Furthermore, the outlet pipe 30 is located downstream of the housing 10 in the gas flow direction X.

[0076] The shapes of the inlet pipe 20 and the outlet pipe 30 are not particularly limited. They can be cylindrical with a circular cross-section perpendicular to the gas flow direction X, or rectangular with a triangular, quadrilateral, pentagonal, or hexagonal cross-section, or elliptical cylindrical with an elliptical cross-section. Among them, the inlet pipe 20 and the outlet pipe 30 are preferably cylindrical.

[0077] The diameters (outer and inner diameters) of the inlet pipe 20 and the outlet pipe 30 are not particularly limited, and can be partially expanded or reduced. This structure facilitates connection to other components or allows for the configuration of other components.

[0078] Materials used for the inlet tube 20 and the outlet tube 30 can be, for example, metals or 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 inlet tube 20 and the outlet tube 30.

[0079] <Particle Generation Section 40>

[0080] The particle generating unit 40 is responsible for generating particles that are introduced into the columnar honeycomb filter 1. The particle generating unit 40 is capable of generating a gas containing the particles. The gas containing the particles is not particularly limited; examples include air, nitrogen, helium, hydrogen, and argon. However, from the perspectives of cost and safety, air is preferred.

[0081] The particles generated by the particle generating unit 40 are not particularly limited, and examples include soot particles, carbon particles, oil particles such as DEHS (bis(2-ethylhexyne sebacic acid)) particles, NaCl particles, and resin particles such as polystyrene latex particles. Devices capable of generating these particles are commercially available, therefore, commercially available devices can be used as the particle generating unit 40.

[0082] There are no particular limitations on the particle generating unit 40; for example, a soot particle generator capable of generating soot particles can be used. The soot particle generator is connected to, for example, a propane source, a nitrogen source, and an air source, and generates soot particles by incompletely burning propane.

[0083] When the particle size distribution of the particles generated by the particle generation unit 40 is close to the particle size distribution of PM contained in actual exhaust gas, the inspection accuracy can be improved. For example, regarding PM contained in automobile exhaust, the median particle size D50 (hereinafter referred to as "average particle size") of the cumulative particle size distribution obtained by electrostatic particle classifiers and agglomerated particle counters is 50 to 100 nm. Therefore, it is ideal that the average particle size of the particles generated by the particle generation unit 40 is also within this range. However, even particles with a particle size distribution different from that of PM contained in actual exhaust gas can be used because the collection mechanism is the same up to 1000 nm.

[0084] Particle capture can be mainly divided into the following four types.

[0085] (I) Diffusion (through the Brownian motion of particles, which causes them to move differently from flow and thus become trapped)

[0086] (II) Obstruction (even if there is physical contact with the object while it is moving, it will still be captured)

[0087] (III) Sedimentation (For larger particles, they are separated from the flow due to gravity and thus cannot pass through)

[0088] (IV) Inertia (For larger particles, even if the direction of flow changes, they do not necessarily collide with and be captured by the flow)

[0089] For particles up to 1000 nm in diameter, diffusion and occlusion are dominant, so by using particles smaller than that, it is possible to simulate actual trapping performance.

[0090] Therefore, the average particle size of the particles generated by the particle generating unit 40 is preferably 100 to 1000 nm. By controlling the average particle size within such a range, the inspection accuracy of the collection performance can be steadily improved.

[0091] Furthermore, when checking the collection performance of a columnar honeycomb filter 1 with general collection capabilities, the average particle size only needs to be within the aforementioned range. However, when checking the collection performance of a columnar honeycomb filter 1 with higher collection capabilities, if the average particle size is 300 nm or more, the results are almost identical, making it difficult to obtain detailed information about the collection performance. Therefore, in such cases, it is preferable to set the average particle size to be 30 nm or more and less than 300 nm, more preferably 100–250 nm. By controlling the average particle size within this range, detailed information about the collection performance can be obtained even when checking a columnar honeycomb filter 1 with higher collection capabilities, thus improving the accuracy of the collection performance inspection.

[0092] <Particle Introduction Section 50>

[0093] The particle introduction section 50 is the part that introduces particles generated by the particle generation section 40 into the introduction tube 20. The particle introduction section 50 and the particle generation section 40 can be connected using a tubular component such as a tube.

[0094] There are no particular limitations on the particle introduction section 50, but from the viewpoint of uniformly introducing particles into the introduction tube 20, a sprayer is preferred.

[0095] The direction of particle introduction in particle introduction section 50 is as follows: Figure 4 As shown, the angle θ relative to the gas flow direction X is preferably greater than 90°, more preferably 100-180°, even more preferably 150-180°, and particularly preferably 180°. Furthermore, Figure 4 yes Figure 1 The enlarged view shows the periphery of the particle introduction section 50. By controlling the particle introduction direction in this way, the particles diffuse more easily into the gas, thus improving the effect of suppressing uneven particle concentration distribution in the plane perpendicular to the gas flow direction X. Furthermore, by using the particles whose uneven concentration distribution has been suppressed, the particle counters 70a and 70b count the number of these particles, thereby further improving the accuracy of the collection performance inspection.

[0096] The particle introduction section 50 preferably has a particle outlet at a position facing the gas flow direction X, and more preferably at a position opposite to the gas flow direction X. By providing the outlet at such a position, particles can be introduced at an angle θ greater than 90° relative to the gas flow direction X.

[0097] The particle introduction amount and introduction speed in the particle introduction section 50 can be set appropriately according to the type of particle introduction section 50 and the size of the introduction tube 20, and there are no special limitations.

[0098] <Gas stirring section 60>

[0099] The gas stirring unit 60 is a component that functions to stir gas. The gas stirring unit 60 is located in the inlet pipe 20 upstream of the particle inlet unit 50 in the gas flow direction X.

[0100] There are no particular limitations on the gas stirring section 60, but a gas stirring plate is preferred.

[0101] Here, in Figure 5 The image shows a typical top view of a gas stirring plate (viewed from the upstream side in the gas flow direction X). Furthermore, in Figure 6 The middle shows Figure 5 A sectional view of line a-a'.

[0102] like Figure 5 As shown in Figure 6, the gas stirring plate 61 has a pair of planes 62a and 62b perpendicular to the gas flow direction X, and forms a plurality of openings 63 that penetrate the pair of planes 62a and 62b.

[0103] By using a gas stirring plate 61 as the gas stirring section 60, a negative pressure is created on the rear flow side (plane 62b side) of the gas stirring plate 61, generating a counter-current flow of gas to form a recirculation flow. By introducing particles from the particle inlet 50 into this section, the particles are entrained in the recirculation flow and diffuse into the gas, thus suppressing uneven particle concentration distribution in the plane perpendicular to the gas flow direction X. As a result, particles can be uniformly supplied to the columnar honeycomb filter 1 of the object being inspected. Furthermore, the gas stirring plate 61 has a simpler structure than stirring devices with rotating blade mechanisms, and does not require external power, thus reducing various costs.

[0104] In the gas stirring plate 61, a plurality of openings 63 are preferably provided in the region on the outer periphery of the gas stirring plate 61. By providing a plurality of openings 63 in such a region, a recirculating flow is easily formed on the downstream side of the gas stirring plate 61, thereby improving the effect of particle diffusion in the gas.

[0105] Here, the area on the outer periphery of the gas stirring plate 61 refers to the area extending from the outer periphery of the gas stirring plate 61 to half the diameter (for example, the radius in the case of a circular plate) of the outer periphery from the center of the gas stirring plate 61.

[0106] In the gas stirring plate 61, the opening ratio of the plurality of openings 63 is preferably 5 to 50%, more preferably 10 to 40%. By controlling the opening ratio to such a degree, a recirculating flow is easily formed on the downstream side of the gas stirring plate 61, thereby improving the effect of particle diffusion in the gas.

[0107] Here, the so-called aperture ratio refers to, for example, in Figure 5 In the top view, the area of ​​the opening 63 is the ratio of the area of ​​the plane 62a to the total area of ​​the opening 63.

[0108] The faster the gas flow rate (the higher the flow rate) in the inlet pipe 20, the easier it is to form a recirculation flow on the back side of the gas stirring plate 61. Therefore, the gas flow rate is preferably 500 to 10000 L / min.

[0109] The size of the gas stirring plate 61 is not particularly limited, as long as it is adjusted appropriately according to the size of the inlet pipe 20 on which the gas stirring plate 61 is installed. For example, the outer diameter of the gas stirring plate 61 can correspond to the inner diameter of the inlet pipe 20.

[0110] As for the material used for the gas stirring plate 61, metals, ceramics, etc., can be used, for example. 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 as the material for the gas stirring plate 61.

[0111] The distance between the particle inlet 50 and the gas stirring section 60 in the gas flow direction X is preferably 3 times or less the inner diameter of the inlet pipe 20 at which the gas stirring section 60 is located, and more preferably 2.5 times or less. By controlling the distance between the particle inlet 50 and the gas stirring section 60 within such a range, particles can be stably introduced into the region where the recirculation flow is formed, thereby improving the effect of particle diffusion in the gas.

[0112] The gas stirred by the gas stirring unit 60 (the gas that carries the particles) is not particularly limited, but examples include air, nitrogen, helium, hydrogen, and argon. Among these, air is preferred from the viewpoints of cost and safety.

[0113] <Particle Detectors 70a, 70b>

[0114] Particle detectors 70a and 70b are devices for measuring the number of particles in the gas flowing through the inlet pipe 20 and the outlet pipe 30. Particle detector 70a is disposed in the inlet pipe 20 downstream of the particle inlet section 50 in the gas flow direction X. Particle detector 70b is disposed in the outlet pipe 30.

[0115] As for the particle counters 70a and 70b, there are no particular limitations as long as they are devices capable of measuring the number of particles contained in a gas. However, when checking the collection performance of the columnar honeycomb filter 1 with high collection capacity, as mentioned above, it is preferable to use particles with a smaller average particle size. In order to perform the measurement of such particles with a smaller average particle size, the particle counters 70a and 70b are preferably selected as devices capable of measuring the number of particles with a particle size of 100 nm or more.

[0116] As particle counters 70a and 70b, for example, optical particle counters, laser photoelectric meters, and dust collectors can be used. Among these, optical particle counters are preferred. By using an optical particle counter, the number of particles can be easily and accurately measured. Furthermore, optical particle counters are commercially available (e.g., RION Corporation's KC-24, KC-22B, etc.), so commercially available products can be used as particle counters 70a and 70b.

[0117] The distance between the particle inlet 50 in the gas flow direction X and the particle detector 70a provided in the inlet pipe 20 is preferably more than twice the inner diameter of the inlet pipe 20 where the particle detector 70a is located. By arranging the particle detector 70a within this range, the number of particles contained in the gas can be accurately measured.

[0118] like Figure 7 As shown, the inspection device 100 for the columnar honeycomb filter 1 according to the embodiment of the present invention can, as needed, also include a diluent 80 for adjusting the particle concentration between the particle generation section 40 and the particle introduction section 50. Such a diluent 80 is commercially available (e.g., TSI Model 3332), therefore, this commercially available product can be used.

[0119] When an optical particle counter is selected as the particle detector 70a, 70b, the optical particle counter is easily contaminated by particles, so it is preferable to reduce the concentration of particles in the gas. Therefore, by providing a diluent 80 between the particle generation section 40 and the particle introduction section 50, the particle concentration can be adjusted, thereby suppressing contamination of the optical particle counter.

[0120] The diluter 80 preferably dilutes the concentration of particles generated by the particle generating unit 40 to 2 to 1000 times. With such a dilution ratio, contamination of the optical particle counter can be stably suppressed.

[0121] like Figure 7 As shown, the inspection device 100 for the columnar honeycomb filter 1 according to the embodiment of the present invention can also be equipped with a calculation unit 90, which calculates the particle collection efficiency based on the number of particles measured by particle counters 70a and 70b provided in the inlet pipe 20 and the outlet pipe 30, as needed. A computer or the like can be cited as an example of such a calculation unit 90.

[0122] By setting up such a computing unit 90, the capture efficiency can be calculated in real time, thus enabling rapid inspection.

[0123] (2) Inspection method for columnar honeycomb filter 1

[0124] The inspection method for the columnar honeycomb filter 1 according to embodiments of the present invention includes: a particle generation step (S1), a particle introduction step (S2), a particle supply step (S3), and a particle measurement step (S4). By performing these steps, the inspection accuracy of the collection performance of the columnar honeycomb filter 1 can be improved. This inspection method can be performed using the aforementioned inspection apparatus 100 for the columnar honeycomb filter 1.

[0125] The particle generation process (S1) is the process of generating particles. This process can be carried out by activating the particle generation unit 40 in the inspection device 100 of the columnar honeycomb filter 1.

[0126] The particle introduction process (S2) is a process of introducing particles generated in the particle generation process (S1) into the gas stirred by the gas stirring unit 60. This process can be performed by introducing particles generated by the particle generation unit 40 into the introduction tube 20 using the particle introduction unit 50 in the inspection device 100 of the columnar honeycomb filter 1. By introducing particles into the gas in this way, the particles can easily diffuse into the gas, thereby suppressing uneven particle concentration distribution.

[0127] In the particle introduction process (S2), the particle introduction direction is preferably at an angle θ greater than 90° relative to the gas flow direction X. By controlling the particle introduction direction in this way, the particles diffuse more easily into the gas, thus improving the effect of suppressing uneven particle concentration distribution in the plane perpendicular to the gas flow direction X.

[0128] The particle supply process (S3) involves supplying a gas containing particles to the columnar honeycomb filter 1. Uneven particle concentration distribution in the gas supplied to the columnar honeycomb filter 1 is suppressed, thus ensuring a uniform particle supply within the filter 1. Consequently, even with variations in the orientation and installation method of the columnar honeycomb filter 1, measurement values ​​are less prone to deviation, thereby improving the accuracy of the collection performance inspection.

[0129] The particle counting process (S4) is a process of counting the number of particles in the gas upstream and downstream of the columnar honeycomb filter 1 in the gas flow direction X. This process is performed using particle counters 70a and 70b in the inspection device 100 of the columnar honeycomb filter 1.

[0130] The inspection method for the columnar honeycomb filter 1 according to the embodiments of the present invention can, as needed, include a particle concentration dilution step (S5) to dilute the concentration of particles generated by the particle generation step (S1). This step can be performed between the particle generation step (S1) and the particle introduction step (S2), and is carried out using a diluent 80 in the inspection apparatus 100 of the columnar honeycomb filter 1.

[0131] The particle concentration dilution step (S5) preferably dilutes the concentration of particles generated by the particle generation step as described above to 2 to 1000 times. Through this step, the particle concentration can be adjusted, thereby suppressing contamination of the optical particle counter.

[0132] The inspection method for the columnar honeycomb filter 1 according to the embodiments of the present invention can, as needed, further include a collection efficiency calculation step (S6) for calculating the collection efficiency of particles based on the number of particles obtained by the particle counting step (S4). The collection efficiency can be calculated using the following formula.

[0133] Collection efficiency [%] = (Number of particles in the gas upstream of columnar honeycomb filter 1 - Number of particles in the gas downstream of columnar honeycomb filter 1) / Number of particles in the gas upstream of columnar honeycomb filter 1 × 100

[0134] The collection efficiency calculation step (S6) can be performed after the particle measurement step (S4) using the calculation unit 90 in the inspection device 100 of the columnar honeycomb filter 1. Through this step, the collection efficiency can be calculated in real time, thus enabling rapid inspection.

[0135] Symbol Explanation

[0136] 1 columnar honeycomb filter

[0137] 2. Peripheral wall

[0138] 3a First end face

[0139] 3b Second end face

[0140] 4a First Compartment

[0141] 4b second compartment

[0142] 5 next door

[0143] 6 sealing section

[0144] 10 Containment Department

[0145] 20 Implantation Tubes

[0146] 30 discharge pipe

[0147] 40-particle production unit

[0148] 50-particle inlet section

[0149] 60 Gas stirring section

[0150] 61 Gas stirring plate

[0151] Planes 62a and 62b

[0152] 63 opening

[0153] 70a and 70b particle meters

[0154] 80 diluent

[0155] 90 Computing Department

[0156] 100 Inspection Device

[0157] The direction of gas flow X.

Claims

1. An inspection apparatus for a columnar honeycomb filter, comprising: a housing portion capable of housing a columnar honeycomb filter; an introduction pipe and an exhaust pipe capable of allowing a gas to flow therethrough and connected to the housing portion; a particle generation portion for generating particles; a particle introduction portion for introducing the particles generated by the particle generation portion into the introduction pipe; a gas stirring portion provided in the introduction pipe on an upstream side of the particle introduction portion in a flow direction of the gas; and a particle counter provided in the introduction pipe and the exhaust pipe on a downstream side of the particle introduction portion in the flow direction of the gas, for counting the number of the particles, wherein the gas stirring portion is a gas stirring plate having a pair of planes perpendicular to the flow direction of the gas and formed with a plurality of opening portions penetrating the pair of planes, wherein a plurality of the opening portions are provided in a region on an outer peripheral side of the gas stirring plate, the region on the outer peripheral side of the gas stirring plate being a region from an outer peripheral portion of the gas stirring plate to a point at a distance of 1 / 2 of a diameter from a center of the gas stirring plate to the outer periphery, wherein an opening ratio of the plurality of the opening portions is 10 to 40%, wherein a flow rate of the gas is 500 to 10,000 L / min, and wherein an introduction direction of the particles in the particle introduction portion has an angle of more than 90° with respect to the flow direction of the gas.

2. The inspection apparatus for a columnar honeycomb filter according to claim 1, wherein an average particle diameter of the particles is 100 to 1,000 nm.

3. The inspection apparatus for a columnar honeycomb filter according to claim 1 or 2, wherein the particle counter is capable of counting the number of the particles having a particle diameter of 100 nm or more.

4. The inspection apparatus for a columnar honeycomb filter according to claim 1 or 2, wherein the particle counter is an optical particle counter.

5. The inspection apparatus for a columnar honeycomb filter according to claim 1 or 2, further comprising a diluter for adjusting a concentration of the particles between the particle generation portion and the particle introduction portion.

6. The inspection apparatus for a columnar honeycomb filter according to claim 5, wherein the diluter dilutes the concentration of the particles generated by the particle generation portion by a factor of 2 to 1,000.

7. The inspection apparatus for a columnar honeycomb filter according to claim 1 or 2, further comprising a calculation portion for calculating a collection efficiency of the particles based on the number of the particles counted by the particle counter provided in the introduction pipe and the exhaust pipe.

8. The inspection apparatus for a columnar honeycomb filter according to claim 1 or 2, wherein a distance between the particle introduction portion and the gas stirring portion in the flow direction of the gas is 3 times or less an inner diameter of the introduction pipe at a position where the gas stirring portion is disposed.

9. The inspection apparatus for a columnar honeycomb filter according to claim 1 or 2, wherein a distance between the particle introduction portion and the particle counter provided in the introduction pipe in the flow direction of the gas is 2 times or more the inner diameter of the introduction pipe at a position where the particle counter is disposed. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10. A method for inspecting a cylindrical honeycomb filter, comprising: a particle generating step of generating particles; a particle introducing step of introducing the particles generated in the particle generating step into a gas stirred by a gas stirring section; a particle supplying step of supplying the gas into which the particles are introduced to a cylindrical honeycomb filter; and a particle measuring step of measuring the number of the particles in the gas on an upstream side and a downstream side of the cylindrical honeycomb filter in a flow direction of the gas, the gas stirring section is a gas stirring plate having a pair of planes perpendicular to the flow direction of the gas and formed with a plurality of opening sections penetrating the pair of planes, the plurality of opening sections are provided in a region of an outer peripheral side of the gas stirring plate, the region of the outer peripheral side of the gas stirring plate being a region from an outer peripheral portion of the gas stirring plate to a point at which a diameter from a center of the gas stirring plate to the outer periphery is 1 / 2, an opening ratio of the plurality of opening sections is 10 to 40%, a flow rate of the gas is 500 to 10,000 L / min, an introduction direction of the particles in the particle introducing step has an angle exceeding 90° with respect to the flow direction of the gas.

11. The method for inspecting a cylindrical honeycomb filter according to claim 10, wherein an average particle diameter of the particles is 100 to 1,000 nm.

12. The method for inspecting a cylindrical honeycomb filter according to claim 10 or 11, wherein the particle measuring step measures the number of the particles having a particle diameter of 100 nm or more.

13. The method for inspecting a cylindrical honeycomb filter according to claim 10 or 11, wherein the number of the particles is measured using an optical particle counter.

14. The method for inspecting a cylindrical honeycomb filter according to claim 10 or 11, wherein the method further comprises a particle concentration diluting step of diluting a concentration of the particles generated in the particle generating step.

15. The method for inspecting a cylindrical honeycomb filter according to claim 14, wherein in the particle concentration diluting step, the concentration of the particles generated in the particle generating step is diluted by 2 to 1,000 times.

16. The method for inspecting a cylindrical honeycomb filter according to claim 10 or 11, wherein the method further comprises a collection efficiency calculating step of calculating a collection efficiency of the particles based on the number of the particles obtained in the particle measuring step. ​

Images