Honeycomb unit and catalyst converter used for purification of exhaust gas

Abstract

To provide a honeycomb unit in which through holes are provided for a flat foil and a wave foil, and purification performance in carrying a catalyst is sufficiently improved.SOLUTION: A honeycomb unit for exhaust gas purification comprises: a honeycomb body which is made of a metal foil and constituted by laminating a flat foil and a wave foil 3 each having a plurality of through holes; and an external cylinder. The center of each through hole 21 of the flat foil is arranged at a different position in a honeycomb body axial direction with respect to the center of each through hole 31 of the wave foil. The flat foil includes a first hole row A constituted of through holes formed at equal intervals in a honeycomb body circumferential direction, and second hole row B adjacent to the first hole row on the first hole row downstream side in an axial direction. The wave foil includes a third hole row C which is constituted of through holes formed at equal intervals in a honeycomb body circumferential direction and arranged between the first hole row and the second hole row. When a face which includes a downstream side end part of the first hole row and is orthogonal to axial direction is a lower end face and a face including an upstream side end part of the second hole row is an upper end face, each through hole constituting the third hole row is arranged over the lower end face and the upper end face.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a honeycomb unit including a honeycomb body and an outer casing, and more particularly to a honeycomb unit used in a catalytic converter that purifies exhaust gas from an internal combustion engine of an automobile or the like. [Background technology]

[0002] A honeycomb unit composed of a honeycomb body formed by laminating flat and corrugated foils and an outer cylinder that houses the honeycomb body is used as a purification device that purifies exhaust gas discharged from an internal combustion engine. The honeycomb body is formed, for example, by alternately laminating flat and corrugated foils, or by winding flat and corrugated foils in an overlapping state around an axis. By disposing a honeycomb unit (also called a catalytic converter) that includes a honeycomb body supporting a catalyst in the exhaust gas path, the exhaust gas passing through the catalytic converter comes into contact with the catalyst, thereby enabling efficient exhaust gas purification.

[0003] A honeycomb unit is known in which through holes are provided in the flat and corrugated foils of a honeycomb body for the purpose of improving purification performance (see Patent Document 1). Patent Document 2 discloses a honeycomb body having cavities formed by overlapping through holes formed in the flat and corrugated foils. According to the honeycomb bodies disclosed in Patent Documents 1 and 2, the exhaust gas passing through the through holes in the honeycomb body becomes a turbulent flow, and the exhaust gas can be efficiently agitated. This makes it easier for the exhaust gas to come into contact with the catalyst supported on the honeycomb body, thereby improving the purification performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2005-535454 [Patent Document 2] Special Publication No. 2008-532735 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the through holes of the flat foil and the corrugated foil are formed at the same axial position of the honeycomb body as in the honeycomb body disclosed in Patent Document 2, the through holes tend to overlap. Since no catalyst is present in the area where the through holes overlap, the catalytic reaction cannot proceed in that area, and there is a risk that the purification performance of the catalytic converter will not be sufficiently improved.

[0006] In view of these points, the present invention aims to provide a honeycomb unit having through holes in flat foil and corrugated foil, which has sufficiently improved purification performance when a catalyst is supported on the honeycomb body. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides (1) a honeycomb unit used for purifying exhaust gas, comprising a honeycomb body formed by laminating flat foil and corrugated foil made of metal foil, the flat foil and the corrugated foil each having a plurality of through holes formed therein, and an outer cylinder for accommodating the honeycomb body. In the honeycomb unit, the centers of the through holes formed in the flat foil are disposed at different positions in the axial direction of the honeycomb body with respect to the centers of the through holes formed in the corrugated foil. The flat foil comprises a first hole row constituted by through holes formed at equal intervals along the circumferential direction of the honeycomb body, and a second hole row constituted by through holes formed at equal intervals along the circumferential direction of the honeycomb body, the second hole row being located downstream of the first hole row and adjacent to the first hole row in the axial direction. The corrugated foil comprises a third hole row constituted by through holes formed at equal intervals along the circumferential direction of the honeycomb body, and disposed at a position corresponding to between the first hole row and the second hole row in the axial direction. When the surface including the downstream end of the first row of holes and extending in a direction perpendicular to the axial direction is defined as the lower end surface, and the surface including the upstream end of the second row of holes and extending in a direction perpendicular to the axial direction is defined as the upper end surface, each of the through holes constituting the third row of holes is arranged astride the lower end surface and the upper end surface.

[0008] (2) A catalytic converter comprising the honeycomb unit according to (1) above and a catalyst supported on the honeycomb body. Effect of the Invention

[0009] A catalytic converter constructed from a honeycomb unit according to the present invention can enjoy the effect of improving purification performance by agitating exhaust gases due to the through holes formed in the flat foil and corrugated foil, while sufficiently improving purification performance by reducing the areas in the honeycomb body where no catalyst is present. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a honeycomb unit 1 according to the present embodiment. [Diagram 2] 1 shows a development view of flat foils 2 and corrugated foils 3 that constitute a honeycomb body 4 in this embodiment. [Diagram 3] 1 shows a development view of the flat foil 2 and the corrugated foil 3 when the through hole 21 of the flat foil 2 and the through hole 31 of the corrugated foil 3 are provided at the same position in the axial direction. [Figure 4] FIG. 2 is a diagram for explaining the definition of the aperture ratio. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a honeycomb unit 1 in this embodiment. Referring to FIG. 1, the honeycomb unit 1 includes a honeycomb body 4 in which flat foils 2 and corrugated foils 3 are alternately laminated, and an outer cylinder 5. The honeycomb body 4 may be formed by alternately laminating the flat foils 2 and the corrugated foils 3, or may be formed by winding the flat foils 2 and the corrugated foils 3 in an overlapping state around an axis. According to the above-mentioned configuration, a large number of gas flow paths 40 extending in the axial direction can be formed inside the honeycomb body 4. In this embodiment, an example is shown in which the honeycomb body 4 is formed by winding the flat foils 2 and the corrugated foils 3 in an overlapping state around an axis.

[0012] The flat foil 2 and the corrugated foil 3 may be made of a metal foil made of a heat-resistant alloy. The corrugated foil 3 may be manufactured by, for example, corrugating a flat metal foil. The foil thickness of the flat foil 2 and the corrugated foil 3 is not particularly limited, but is preferably 20 μm to 100 μm. The cell density of the honeycomb body 4 is not particularly limited, but is preferably 100 to 600 cells per square inch. The flat foil 2 and the corrugated foil 3 are joined by brazing, for example, using a Ni-based brazing material having high heat resistance, but the joining method is not limited thereto.

[0013] The heat-resistant alloy constituting the flat foil 2 and the corrugated foil 3 is preferably Fe-20Cr-5Al stainless steel, but is not limited thereto, and various heat-resistant stainless steels containing Al in the alloy composition can be used. Usually, the metal foil used in the honeycomb body 4 contains 15-25 mass% Cr and 2-8 mass% Al. Therefore, for example, Fe-18Cr-3Al alloy and Fe-20Cr-8Al alloy can be used as the heat-resistant alloy.

[0014] For the outer cylinder 5, a ferritic stainless steel containing about 13 to 20 mass % of Cr, such as SUS436L or SUS430, can be used. The thickness of the outer cylinder 5 is not particularly limited, but is preferably 1 to 2 mm. The honeycomb body 4 and the outer cylinder 5 are joined by brazing using, for example, a Ni-based brazing material having high heat resistance, but the joining method is not limited to this.

[0015] A specific washcoat liquid is applied to the wall surface of the gas flow passage 40 formed in the honeycomb body 4, and then the liquid is dried and fired, thereby making the flat foil 2 and the corrugated foil 3 carry the catalyst. For example, the washcoat liquid may be a slurry obtained by stirring gamma alumina powder, lanthanum oxide, zirconium oxide, and cerium oxide in an aqueous solution of palladium nitrate.

[0016] The honeycomb unit 1 (catalytic converter) carrying the catalyst is connected to an exhaust pipe of a vehicle (not shown) so that exhaust gas flowing in from an inlet end 1A can be discharged to an outlet end 1B. When the exhaust gas flowing into the gas flow passages 40 of the honeycomb body 4 comes into contact with the catalyst carried on the wall surface of each gas flow passage 40, carbon monoxide, hydrocarbons, and nitrogen oxides in the exhaust gas are rendered harmless through oxidation or reduction reactions, and the exhaust gas is purified.

[0017] The through holes provided in the flat foil 2 and the corrugated foil 3 will be described below with reference to Fig. 2. Fig. 2 shows a development of the flat foil 2 and the corrugated foil 3 that constitute the honeycomb body 4 in this embodiment. For ease of explanation, the flat foil 2 is shown without showing the foil parts other than the through holes 21. The longitudinal direction and transverse direction of the corrugated foil 3 shown in Fig. 2 correspond to the circumferential direction and axial direction of the honeycomb body 4, respectively.

[0018] 2, the flat foil 2 has a plurality of through holes 21 formed therethrough in the thickness direction, and the corrugated foil 3 has a plurality of through holes 31 formed therethrough in the thickness direction. The through holes 21 formed in the flat foil 2 (not shown) are indicated by solid lines, and the through holes 31 formed in the corrugated foil 3 are indicated by dashed lines. Although the through holes 31 are circular, in principle they have a roughly elliptical shape when the corrugated foil 3 is viewed in plan as in FIG. 2. In this embodiment, the diameter of the through holes 21 formed in the flat foil 2 and the diameter of the through holes 31 formed in the corrugated foil 3 are set to be the same. In the following description, when the through holes 21 and the through holes 31 are not distinguished from each other, the through holes 21 and 31 are collectively referred to as the through hole 100.

[0019] When the flat foil 2 and the corrugated foil 3 do not have the through holes 100, the flow state of the exhaust gas passing through each gas flow passage 40 of the honeycomb body 4 is basically laminar. Therefore, the reactant molecules of the gas flowing near the wall surface of the gas flow passage 40 come into contact with the catalyst and are purified, while the reactant molecules of the exhaust gas flowing near the center of the gas flow passage do not come into contact with the wall surface of the gas flow passage and are not purified. Since the reaction rate of the catalytic reaction increases as the concentration of the reactants increases, when the flow state of the exhaust gas passing through each gas flow passage 40 is laminar, the gas concentration near the wall surface is significantly lower than that near the center of the gas flow passage, and the reaction efficiency of the catalyst is reduced. As a result, the exhaust gas cannot be purified efficiently.

[0020] Therefore, by providing the through holes 100 in the flat foil 2 and the corrugated foil 3, the flow state of the exhaust gas becomes turbulent when passing through the through holes 100, and the exhaust gas is agitated. This makes the concentration of the exhaust gas uniform near the wall surface and near the center of the gas flow path 40, and therefore the exhaust gas can be efficiently purified.

[0021] Here, consider a configuration in which each through hole 21 of the flat foil 2 and each through hole 31 of the corrugated foil 3 are provided at the same position in the axial direction, as in Patent Document 2. Fig. 3 shows a developed view of the flat foil 2 and the corrugated foil 3 when the through hole 21 of the flat foil 2 and the through hole 31 of the corrugated foil 3 are provided at the same position in the axial direction. "The through hole 21 of the flat foil 2 and the through hole 31 of the corrugated foil 3 are provided at the same position in the axial direction" refers to a state in which the center of the through hole 21 of the flat foil 2 and the center of the through hole 31 of the corrugated foil 3 coincide in the axial direction.

[0022] 3, when the through holes 21 in the flat foil 2 and the through holes 31 in the corrugated foil 3 are provided at the same position in the axial direction, the total area of ​​the overlapping region where the through holes 21 in the flat foil 2 and the through holes 31 in the corrugated foil 3 overlap becomes excessively large. Since no catalyst is present in either the flat foil 2 or the corrugated foil 3 in the overlapping region, the catalytic reaction cannot proceed in this region, and the purification performance of the exhaust gas is not sufficiently improved.

[0023] Therefore, the present inventors conducted extensive research to reduce the total area of ​​the overlapping regions. As a result, they came up with a configuration (hereinafter also referred to as a shift configuration) in which the positions of the through holes 21 of the flat foil 2 and the positions of the through holes 31 of the corrugated foil 3 are made different in the axial direction, as shown in Fig. 2. Here, "making the positions of the through holes 21 of the flat foil 2 and the positions of the through holes 31 of the corrugated foil 3 different in the axial direction" refers to a state in which the centers of the through holes 21 of the flat foil 2 are arranged at different positions relative to the centers of the through holes 31 of the corrugated foil 3 in the axial direction.

[0024] According to the shift configuration of the present invention, the overlapping region where the through holes 21 and the through holes 31 overlap is narrower than in a configuration in which the through holes 21 of the flat foil 2 and the through holes 31 of the corrugated foil 3 are provided at the same position in the axial direction (see FIG. 3). Therefore, in the honeycomb body 4, the region in which the catalyst is present in either the flat foil 2 or the corrugated foil 3 can be made larger, thereby improving the purification performance of the exhaust gas. However, if the distance in the axial direction between the center of the through hole 21 of the flat foil 2 and the center of the through hole 31 of the corrugated foil 3 is small, the overlapping region is not narrowed sufficiently, and the purification performance cannot be sufficiently improved. Therefore, the present inventors conducted further studies and came up with the following configuration.

[0025] That is, in this embodiment, the flat foil 2 includes a first hole row A composed of through holes 21a formed at equal intervals along the circumferential direction of the honeycomb body 4, and a second hole row B composed of through holes 21b formed at equal intervals along the circumferential direction. The second hole row B is located downstream of the first hole row A and is adjacent to the first hole row A in the axial direction. The corrugated foil 3 also includes a third hole row C composed of through holes 31a formed at equal intervals along the circumferential direction of the honeycomb body 4. The third hole row C is disposed at a position corresponding to between the first hole row A and the second hole row B in the axial direction. In other words, the center of each through hole 31a constituting the third hole row C is disposed between the center of each through hole 21a constituting the first hole row A and the center of each through hole 21b constituting the second hole row B in the axial direction.

[0026] In the honeycomb body 4, the surface including the downstream end of the first hole row A and extending in a direction perpendicular to the axial direction is called the "lower end surface", and the surface including the upstream end of the second hole row B and extending in a direction perpendicular to the axial direction is called the "upper end surface". The lower end surface and the upper end surface are shown in FIG. 1 as imaginary surfaces by dashed lines. The lower end surface and the upper end surface shown in FIG. 1 include dashed lines P and Q in the development shown in FIG. 2, respectively. Each through hole 31a constituting the third hole row C is arranged across the lower end surface and the upper end surface. According to this configuration, the overlapping area between the through holes 21a and 21b and the through hole 31a can be sufficiently narrowed, so that the area in which the catalyst is present in either the flat foil 2 or the corrugated foil 3 can be sufficiently large, and the purification performance can be sufficiently improved.

[0027] In this embodiment, the through holes 21 of the flat foil 2 and the through holes 31 of the corrugated foil 3 are arranged in a staggered pattern. However, the arrangement of the through holes 21 of the flat foil 2 and the through holes 31 of the corrugated foil 3 is not limited to this, and may be arranged in a matrix pattern, for example.

[0028] The diameter of the through holes 21 provided in the flat foil 2 is not particularly limited, but is preferably larger than the pitch length T of the cells in the honeycomb body 4 (the distance between the vertices of the cells, which corresponds to the wavelength of the waves in the corrugated foil 3). With this configuration, the through holes 21 are formed so as to straddle the gas flow paths 40 formed adjacent to each other in the circumferential direction of the honeycomb body 4, so that the exhaust gas flowing within the honeycomb body 4 is more agitated, and the purification performance can be further improved.

[0029] The diameter of the through holes 100 provided in the flat foil 2 and the corrugated foil 3 is preferably four times or less the cell pitch length. With this configuration, the size of the through holes 100 is not excessively large, which means that the area without catalyst can be made small. On the other hand, laminarization of the exhaust gas flowing through the through holes 100 can be sufficiently suppressed, so that the exhaust gas flowing inside the honeycomb body 4 is more agitated, and the purification performance can be further improved.

[0030] The aperture ratio of the through holes 100 is not particularly limited, but is preferably 20% or more and 60% or less. With this configuration, the exhaust gas flowing through the honeycomb body 4 is more agitated, and the purification performance can be further improved. Here, the aperture ratio will be explained with reference to FIG. 4. FIG. 4 is a diagram for explaining the definition of the aperture ratio. A triangle is drawn with the center O of three adjacent through holes 100 formed in the same foil as a vertex, and the area of ​​the triangle is defined as the total area, and the area of ​​the portion where the triangle and the through holes 100 overlap is defined as the hole area. In this case, the aperture ratio is calculated as the "ratio of the hole area to the total area."

[0031] The foil thickness, cell density, pore size, porosity, amount of precious metal in the catalyst, etc. can be appropriately selected depending on the required purification performance, pressure loss, strength of the honeycomb body 4, cost, etc.

[0032] (Example) The present invention will be described in more detail below with reference to examples.

[0033] <Examples 1 to 5> In Examples 1 to 5, holes of a predetermined diameter were drilled in two 50 μm-thick sheets of ferritic stainless steel foil (Fe-20Cr-5Al alloy) with a width of 100 mm so that the hole ratio was 40%. The diameter of the through hole was 2.5 mm in Example 1, 3 mm in Example 2, 4 mm in Example 3, 6 mm in Example 4, and 8 mm in Example 5.

[0034] The foil constituting the flat foil was perforated so that no through holes were formed within a range of 3 mm from the region corresponding to the gas inlet side. On the other hand, the foil constituting the corrugated foil was perforated so that the center of the through hole of the flat foil and the center of the through hole of the corrugated foil were at different positions in the axial direction when forming the honeycomb body, and then corrugated to a pitch length of 2.88 mm and a height of 1.44 mm. The distance between the center of the through hole of the flat foil and the center of the through hole of the corrugated foil in the axial direction was 1.6 mm in Example 1, 2 mm in Example 2, 2.6 mm in Example 3, 3.9 mm in Example 4, and 5.2 mm in Example 5. As a result, the catalytic converters of Examples 1 to 5 all had the configuration in the above-mentioned embodiment in which "each through hole 31a constituting the third hole row C is arranged across the lower end surface and the upper end surface."

[0035] A predetermined number of rows of through holes (Example 1: 24 rows, Example 2: 20 rows, Example 3: 15 rows, Example 4: 10 rows, Example 5: 8 rows) were arranged in a staggered pattern in the width direction (i.e., the gas flow direction) of the flat foil and corrugated foil.

[0036] The honeycomb body made by overlapping and winding the flat and corrugated foils obtained in the above process was placed in a stainless steel outer cylinder with an outer diameter of 50 mm, a thickness of 1.5 mm, and a length of 100 mm, and the flat and corrugated foils, as well as the honeycomb body and the outer cylinder, were bonded by vacuum heat treatment at 1200°C for 10 minutes using a pre-applied brazing material (JIS standard BNi-5) to produce a honeycomb unit. The cell density of the honeycomb body was 300 cells per square inch.

[0037] Then, a washcoat solution containing ceria-zirconia-lanthana-alumina as the main component and 1.25 g of palladium per 100 g was passed through the honeycomb unit, and after removing excess washcoat solution, the honeycomb unit was dried at 180°C for 1 hour and then fired at 500°C for 2 hours, thereby carrying a washcoat layer on the flat foil and corrugated foil in an amount of 200 g / L after drying per volume of the honeycomb body, thereby producing a catalytic converter. The amount of palladium carried was 2.5 g / L.

[0038] <Reference examples 1~5> In Reference Examples 1 to 5, both the flat foil and the corrugated foil were drilled so that no through holes were formed within a range of 3 mm from the region corresponding to the gas inlet side, and catalytic converters were manufactured in which the centers of the through holes in the flat foil and the corrugated foil were positioned at the same position in the axial direction of the honeycomb body. Reference Examples 1 to 5 were the same as Examples 1 to 5, respectively, except for the positional relationship between the centers of the through holes in the flat foil and the corrugated foil.

[0039] <Comparative Examples 1 to 5> In Comparative Examples 1 to 5, catalytic converters were manufactured by changing the axial distance between the center of the through hole of the flat foil and the center of the through hole of the corrugated foil compared to Examples 1 to 5 (Comparative Example 1: 0.7 mm, Comparative Example 2: 0.9 mm, Comparative Example 3: 1.2 mm, Comparative Example 4: 1.8 mm, Comparative Example 5: 2.4 mm). In Comparative Examples 1 to 5, the other aspects were the same as in Examples 1 to 5. As a result, the catalytic converters of Comparative Examples 1 to 5 were configured as in the above embodiment, where "each through hole 31a constituting the third hole row C is arranged across the lower end surface", but were not configured as "each through hole 31a constituting the third hole row C is arranged across the upper end surface".

[0040] <Examples 6 to 9> In Examples 6 to 9, catalytic converters were manufactured by changing the diameter of the through hole to 4 mm and the aperture ratio (Example 6: 20%, Example 7: 30%, Example 8: 50%, Example 9: 60%) compared to Examples 1 to 5. The distance between the center of the through hole of the flat foil and the center of the through hole of the corrugated foil in the axial direction was 3.7 mm in Example 6, 3 mm in Example 7, 2.3 mm in Example 8, and 2.1 mm in Example 9. In the width direction of the flat foil and the corrugated foil (i.e., the gas flow direction), a predetermined number of rows of through holes (Example 6: 11 rows, Example 7: 13 rows, Example 8: 17 rows, Example 9: 19 rows) were arranged in a staggered pattern. In Examples 6 to 9, the other conditions were the same as Examples 1 to 5. As a result, the catalytic converters of Examples 6 to 9 were configured such that "each of the through holes 31a constituting the third hole row C is arranged across the lower end surface and the upper end surface" in the above-mentioned embodiment.

[0041] <Reference examples 6~9> In Reference Examples 6 to 9, both the flat foil and the corrugated foil were drilled so that no through holes were formed within a range of 3 mm from the region corresponding to the gas inlet side, and catalytic converters were manufactured in which the centers of the through holes in the flat foil and the corrugated foil were positioned at the same position in the axial direction of the honeycomb body. Reference Examples 6 to 9 were the same as Examples 6 to 9, respectively, except for the positional relationship between the centers of the through holes in the flat foil and the corrugated foil.

[0042] <Evaluation method> The catalytic converters manufactured in Examples 1 to 9, Comparative Examples 1 to 5, and Reference Examples 1 to 9 were evaluated for purification performance by the following method. A model gas (molar fraction: carbon monoxide: 5000 ppm, propylene: 500 ppm, nitrogen monoxide: 500 ppm, oxygen: 4500 ppm, carbon dioxide: 14%, water vapor: 10%, and the remainder nitrogen) was heated from room temperature at a rate of 3°C per minute, and the standard space velocity (the flow rate per unit time when the exhaust gas is at 0°C and 1 atm divided by the capacity of the catalytic converter) was 100,000 hr -1 The flow rate was set so that the mixture was allowed to flow into each catalytic converter. The temperature at which the propylene concentration had decreased by 80% (80% purification temperature) was then evaluated as purification performance. In other words, the lower the 80% purification temperature, the better the purification performance.

[0043] As an index of evaluation, a reference example having the same pore size and porosity as an arbitrary example was used as a standard reference example, and a reduction in the 80% purification temperature of the arbitrary example relative to the standard reference example was evaluated as "B" if it was less than 1°C, evaluated as "A" if it was more than 1°C and less than 5°C, and evaluated as "AA" if it was 5°C or more. For example, for Example 1, Reference Example 1 having the same pore size and porosity as Example 1 was used as the standard reference example.

[0044] The experimental conditions and results of each example are shown in Table 1. In the table, the "shift amount" refers to the smaller of the distances between the center of the through hole of the flat foil and the center of the through hole of the corrugated foil in the axial direction. [Table 1]

[0045] Referring to Table 1, Example 1 was rated "A", whereas Examples 2 to 5 were rated "AA". The reason that Example 1 was only rated "A" is believed to be that the hole diameter was smaller than the pitch length of the corrugated foil, and the stirring effect was insufficient. In Comparative Examples 1 to 5, the distance in the axial direction between the center of the through hole in the flat foil and the center of the through hole in the corrugated foil was short, and therefore the evaluation was "B." In Examples 6 to 9, the evaluation was "AA", and sufficient improvement in purification performance was observed. [Explanation of symbols]

[0046] 1: Honeycomb unit 2: Flat foil 3: Corrugated foil 4: Honeycomb body 5: Outer cylinder 100: Through hole

Claims

1. A honeycomb unit used for purifying exhaust gas includes a honeycomb body formed by laminating flat and corrugated metal foils, the flat and corrugated metal foils each having a plurality of through holes, and an outer cylinder for accommodating the honeycomb body, The centers of the through holes formed in the flat foil are disposed at different positions in the axial direction of the honeycomb body relative to the centers of the through holes formed in the corrugated foil, The flat foil is a first hole row composed of through holes formed at equal intervals along a circumferential direction of the honeycomb body; a second hole row that is formed of through holes that are equally spaced along the circumferential direction of the honeycomb body, the second hole row being located downstream of the first hole row and adjacent to the first hole row in the axial direction; Equipped with The corrugated foil is a third hole row, the third hole row being constituted by through holes formed at equal intervals along the circumferential direction of the honeycomb body and disposed at a position corresponding to between the first hole row and the second hole row in the axial direction; When a surface including a downstream end of the first row of holes and extending in a direction perpendicular to the axial direction is defined as a lower end surface, and a surface including an upstream end of the second row of holes and extending in a direction perpendicular to the axial direction is defined as an upper end surface, The through holes constituting the third row of holes are disposed across the lower end surface and the upper end surface. The honeycomb unit is characterized by the above.

2. The honeycomb unit according to claim 1 ; A catalyst supported on the honeycomb body; A catalytic converter comprising:

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