Honeycomb unit and catalyst converter

Abstract

To enhance the durability of an exhaust gas purification honeycomb unit.SOLUTION: In a catalyst carrier formed by joining a honeycomb body which is formed by winding a metal-made flat foil and a wavy foil and a part of an outer cylinder, when defining a joining part between the flat foil and the wavy foil, being a joining part arranged at an external peripheral side face of the flat foil as a first joining part, defining a joining part arranged at an internal peripheral side face of the flat face as a second joining part, and defining a joining part between the honeycomb body and the outer cylinder as a third joining part, the first joining part, the second joining part and the third joining part are arranged in an input-side region, one joining part out of the first joining part, the second joining part and the third joining part is arranged in a position which is offset to the other two joining regions, the other two joining regions are arranged in the same position or the offset position, and the first joining part or the second joining part is arranged in an output-side region of an exhaust gas.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a honeycomb unit and a catalytic converter having excellent structural durability. [Background technology]

[0002] In recent years, catalyst carriers (particularly those called metal carriers) made by fitting a honeycomb body made of a heat-resistant alloy into an outer cylinder made of the same alloy have been widely used as catalyst carriers for catalytic converters in internal combustion engines of automobiles, etc. The honeycomb body is formed by alternately laminating flat foils with a thickness of about 50 μm and corrugated foils obtained by corrugating the flat foils, and the honeycomb body is either one in which flat foils and corrugated foils are alternately laminated or one in which strip-shaped flat foils and corrugated foils are overlapped and wound in a spiral shape.

[0003] In recent years, automobile exhaust gas regulations have become increasingly strict, making it necessary to activate catalysts quickly. Due to the nature of the engine, catalytic converters are often placed directly under the internal combustion engine. This increases the chances that the catalytic converter will be exposed to high temperatures, making it suitable for use in very harsh environments. As a result, the demands on the structural durability of the metal carriers are becoming more stringent. In order to obtain a carrier with high structural durability, it is necessary to devise a joint structure inside the metal carrier. An example of such a joint structure that can obtain high structural durability is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2021 / 070691 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a honeycomb unit having a simple joint structure and excellent structural durability. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides (1) a honeycomb unit for purifying exhaust gas, which is formed by joining a honeycomb body formed by winding metallic flat foil and corrugated foil to a metallic outer tube surrounding the outer peripheral surface of the honeycomb body, wherein when the joint between the flat foil and the corrugated foil, where the joint arranged on the outer peripheral surface of the flat foil is defined as a first joint, the joint arranged on the inner peripheral surface of the flat foil is defined as a second joint, and the joint between the honeycomb body and the outer tube is defined as a third joint, the first joint, the second joint, and the third joint are arranged in an exhaust gas inlet region, and one of these first joint, second joint, and third joint is arranged in an offset position relative to the other two joints in the axial direction of the honeycomb body, and the other two joints are arranged in the same position or offset positions from each other in the axial direction of the honeycomb body, and the first joint or the second joint is arranged in an exhaust gas outlet region.

[0007] (2) The honeycomb unit according to (1) above, further comprising a third joint portion disposed in the exhaust gas outlet region.

[0008] (3) The honeycomb unit according to (1) or (2) above, characterized in that in an exhaust gas inlet region, the first bonding portion and the third bonding portion are disposed at the same position in the axial direction of the honeycomb body, the second bonding portion is disposed at a position offset from the first bonding portion and the third bonding portion in the axial direction of the honeycomb body, and in an exhaust gas outlet region, there is no first bonding portion but only the second bonding portion is disposed.

[0009] (4) The honeycomb unit according to any one of (1) to (3) above, characterized in that the flat foil and / or the corrugated foil has a plurality of through holes formed therein.

[0010] (5) A catalytic converter comprising a honeycomb unit according to any one of (1) to (4) above, on which a catalyst is supported. Effect of the Invention

[0011] According to the present invention, it is possible to provide a honeycomb unit having a simple joint structure and excellent structural durability. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a view of the honeycomb unit as viewed from the axial direction. [Diagram 2] FIG. 2 is an AA′ cross-sectional view of the honeycomb unit (first embodiment). [Figure 3A] 5 is another cross-sectional view of the honeycomb unit in which the second and third bonding portions are partially overlapped (first embodiment). FIG. [Figure 3B] 5 is another cross-sectional view of the honeycomb unit having second and third bonding portions with different lengths (first embodiment). FIG. [Figure 4] 5 is another cross-sectional view of the honeycomb unit in which the second and third bonding portions are partially overlapped (first embodiment). FIG. [Diagram 5] 5 is another cross-sectional view of the honeycomb unit in which the positions of the first to third bonding portions are all offset (first embodiment). FIG. [Figure 6] 6 is another cross-sectional view of the honeycomb unit in which the third bonding portion in the outlet region is omitted (first embodiment). FIG. [Figure 7] 6 is another cross-sectional view of the honeycomb unit in which the first bonding portion and the third bonding portion in the outlet region are offset (first embodiment). FIG. [Figure 8] FIG. 11 is another cross-sectional view of the honeycomb unit in which the second and third bonding portions in the outlet region are disposed at non-offset positions (second embodiment). [Figure 9] 13 is another cross-sectional view of the honeycomb unit in which the third bonding portion in the outlet region is omitted (second embodiment). FIG. [Figure 10] FIG. 11 is another cross-sectional view of a honeycomb unit in which the second and third bonding portions in the outlet region are disposed at offset positions (second embodiment); [Figure 11] FIG. 2 is a plan view of the punched foil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the honeycomb unit of the present invention will be described with reference to the drawings. FIG. 1 is a view of the honeycomb unit 1 as viewed from the axial direction. Referring to the same figure, the honeycomb unit 1 includes a honeycomb body 10 and an outer cylinder 20. The outer cylinder 20 is formed in a cylindrical shape and is disposed at a position surrounding the outer surface of the honeycomb body 10 in the radial direction. The flat foil 40 and the corrugated foil 30 constituting the honeycomb body 10 can be made of a heat-resistant alloy. The heat-resistant alloy can be a heat-resistant alloy containing 15 to 25 mass% of Cr and 2 to 8 mass% of Al. For example, a heat-resistant alloy such as an Fe-20Cr-5Al alloy can be used. The material constituting the outer cylinder 20 can be, for example, SUS436L, SUS430, or ferritic stainless steel containing about 13 to 20 mass% of Cr, such as EN standard 1.4509. The honeycomb unit 1 can be installed, for example, in an exhaust gas passage of a vehicle. The vehicle includes a two-wheeled vehicle, a four-wheeled vehicle, and an off-road vehicle.

[0014] The honeycomb body 10 is constructed by winding the corrugated foil 30 and the flat foil 40, which is a strip of brazing material arranged in a stacked state, around the axial direction, to form a honeycomb structure in which the corrugated foils 30 and the flat foils 40 are alternately stacked in the radial direction. With the above-mentioned configuration, it is possible to form a large number of gas flow paths extending in the axial direction inside the honeycomb body 10. The "axial direction" corresponds to the direction normal to the paper surface of FIG. 1. The brazing material is also arranged at the intended joining position between the honeycomb body 10 and the outer tube 20.

[0015] The cell density of the honeycomb body 10 is preferably 100 to 600 cells per square inch, and more preferably 300 to 400 cells per square inch. The foil thickness of the flat foil 40 and the corrugated foil 30 is preferably 20 μm or more and 100 μm or less, and more preferably 30 μm or more and 50 μm or less. The thickness (wall thickness) of the outer cylinder 20 is preferably 0.5 mm to 3 mm, and more preferably 1 mm to 2 mm.

[0016] The honeycomb body 10 is inserted into the outer cylinder 20 and heated in a vacuum atmosphere, and the honeycomb body 10 and the outer cylinder 20 are joined via the brazing material (forming a third joint 50 described below) and the corrugated foil 30 and the flat foil 40 are joined (forming a flat foil-corrugated foil joint 60 described below), thereby producing the honeycomb unit 1. A foil brazing material can be used as the brazing material, and for example, a nickel-based brazing material such as BNi-2 or BNi-5 can be used. However, a powdered or granular brazing material other than the foil brazing material can also be used.

[0017] A catalyst (not shown) is supported on the corrugated foil 30 and flat foil 40 that constitute the honeycomb unit 1 to form a catalytic converter. The catalyst can be supported by supplying a washcoat liquid (a solution containing gamma alumina, additives, and a precious metal catalyst) to the gas flow passage of the honeycomb body 10 and baking it by heat treatment.

[0018] When the exhaust gas that has flowed into the gas flow passages of the honeycomb body 10 comes into contact with the catalyst, the CO, hydrocarbons, and NOx contained in the exhaust gas are rendered harmless, making it possible to discharge clean exhaust gas outside the vehicle.

[0019] 2 is a cross-sectional view of the honeycomb unit 1 taken along the dotted line in FIG. 1 along the line AA' of the honeycomb unit 1. Note that AA' passes through the axial center of the honeycomb unit 1. Referring to the figure, in the exhaust gas inlet region, there are formed a flat foil-corrugated foil joint 60 that joins the flat foil 40 and the corrugated foil 30 together, and a third joint 50 that joins the outer tube 20 and the honeycomb body 10 together. The exhaust gas inlet region is defined as the region from the gas inlet edge 11 to 1 / 3 of the total length of the honeycomb body 10. The flat foil-corrugated foil joint 60 and the third joint 50 are contained in the exhaust gas inlet region.

[0020] The flat foil-corrugated foil joint 60 includes a first joint 61 and a second joint 62. The first joint 61 is disposed on the outer peripheral surface 40b of the flat foil 40. The second joint 62 is disposed on the inner peripheral surface 40a of the flat foil 40. In other words, in the radial direction of the honeycomb body 10, the joint used to join the flat foil 40 to the corrugated foil 30 arranged adjacent to the radially outer side of the flat foil 40 is the first joint 61, and the joint used to join the flat foil 40 to the corrugated foil 30 arranged adjacent to the radially inner side of the flat foil 40 is the second joint 62.

[0021] Here, one of the first joint 61, the second joint 62, and the third joint 50 is disposed at a position offset from the other two joints in the axial direction of the honeycomb body 10, and the other two joints are disposed at the same position (hereinafter also referred to as a non-offset position) or at an offset position (hereinafter also referred to as an offset position) relative to each other in the axial direction of the honeycomb body 10. Variations in the positions at which the joints are disposed will be described in detail.

[0022] Referring to Figure 2, the second joint 62 may be arranged at an offset position on the exhaust gas outlet side relative to the first joint 61 and the third joint 50, and the first joint 61 and the third joint 50 may be arranged at non-offset positions relative to each other. Here, the term "offset" also includes a case in which the second joint portion 62 and the first joint portion 61 (third joint portion 50) partially overlap in the radial direction, as exemplified in FIG. 3A. In addition, joints having different lengths are considered to be disposed in an “offset position.” As illustrated in FIG 3B, the third joint 50 is formed to be longer than the second joint 62, so the second joint 62 and the third joint 50 are considered to be disposed in an “offset position.” The definition of "offset" is the same below.

[0023] With reference to FIG. 4, the second joint portion 62 may be disposed at a position offset toward the exhaust gas inlet side from the first joint portion 61 and the third joint portion 50. In FIG. Furthermore, the first bonding portion 61 may be disposed at an offset position relative to the second bonding portion 62 and the third bonding portion 50, and the second bonding portion 62 and the third bonding portion 50 may be disposed at a non-offset position. The third bonding portion 50 may be disposed at an offset position relative to the first bonding portion 61 and the second bonding portion 62, and the first bonding portion 61 and the second bonding portion 62 may be disposed at a non-offset position.

[0024] In addition, the first joint 61, the second joint 62, and the third joint 50 may all be disposed at offset positions. For example, as shown in Fig. 5, the second joint 62, the third joint 50, and the first joint 61 may be disposed in this order from the exhaust gas inlet side. Furthermore, without being limited to this, the second joint 62, the first joint 61 and the third joint 50 may be arranged in this order from the exhaust gas inlet side, or the first joint 61, the second joint 62 and the third joint 50 may be arranged in this order, or the first joint 61, the third joint 50 and the second joint 62 may be arranged in this order, or the third joint 50, the first joint 61 and the second joint 62 may be arranged in this order, or the third joint 50, the second joint 62 and the first joint 61 may be arranged in this order.

[0025] The first joint portion 61, the second joint portion 62 and the third joint portion 50 may have the same width (length in the axial direction of the honeycomb body) or may have different widths.

[0026] 1 to 5, the exhaust gas outlet region is formed with a third joint portion 50 and a first joint portion 61 that are contained within this region. The exhaust gas outlet region can be defined as a region extending from the gas outlet edge portion 12 to 1 / 3 of the total length of the honeycomb body 10.

[0027] The third joint 50 and the first joint 61 disposed in the exhaust gas outlet region are disposed at non-offset positions. Unlike the exhaust gas inlet region, the exhaust gas outlet region does not have the second joint 62. However, as shown in FIG. 6, the third bonding portion 50 in the exit region may be omitted. Furthermore, the third joint 50 and the first joint 61 in the outlet region may be disposed in offset positions relative to each other. Fig. 7 illustrates an example of the third joint 50 and the first joint 61 disposed in offset positions, with the first joint 61 offset toward the exhaust gas outlet side relative to the third joint 50. However, the third joint 50 may also be offset toward the exhaust gas outlet side relative to the first joint 61. The meaning of offset has been described above, and therefore will not be repeated.

[0028] Second embodiment 8 is a cross-sectional view of the honeycomb unit of this embodiment. There are various variations in the arrangement of the first bonding portion 61, the second bonding portion 62, and the third bonding portion 50 disposed in the exhaust gas inlet region, and as these variations have been described in the first embodiment, detailed description thereof will be omitted. The present embodiment differs from the first embodiment in that the exhaust gas outlet region is provided with the third joint portion 50 and the second joint portion 62 contained within this region, and the first joint portion 61 is omitted. The exhaust gas outlet region can be defined as a region extending from the gas outlet edge portion 12 to 1 / 3 of the total length of the honeycomb body 10.

[0029] The third bonding portion 50 and the second bonding portion 62 in the outlet region are disposed at non-offset positions relative to each other. However, as shown in FIG. 9, the third bonding portion 50 may be omitted. Furthermore, the third joint 50 and the second joint 62 in the outlet region may be disposed in offset positions relative to each other. Fig. 10 illustrates the third joint 50 and the second joint 62 disposed in offset positions, with the second joint 62 offset toward the exhaust gas outlet side from the third joint 50. However, the third joint 50 may also be offset toward the exhaust gas outlet side from the second joint 62. The meaning of offset has been described above, and will not be repeated here.

[0030] (Variation 1) In the above-described first and second embodiments, through holes may be formed in at least one of the flat foil 40 and the corrugated foil 30. Since it is "at least one," through holes may be formed only in the flat foil 40, or only in the corrugated foil 30, or through holes may be formed in both the flat foil 40 and the corrugated foil 30. The shape of the hole is not particularly limited, but is preferably circular, and may be slit-shaped or elliptical.

[0031] 11 is a development view of a flat foil for explaining the arrangement region of the through holes. This flat foil may be the flat foil 40, or may be the flat foil before being processed into the corrugated foil 30. Referring to the figure, the through holes 70 are formed in a hole formation region D that avoids the inlet edge region T1 near the gas inlet edge 11 and the outlet edge region T2 near the gas outlet edge 12.

[0032] The inlet edge region T1 is preferably set to 15 mm or less downstream from the gas inlet edge 11. The lower limit of the inlet edge region T1 is not particularly limited, but is preferably set to 1 mm. The outlet side edge region T2 is preferably set to 15 mm or less upstream from the gas outlet side edge 12. The lower limit of the outlet side edge region T2 is not particularly limited, but is preferably set to 1 mm.

[0033] In the hole formation region D, the ratio of the total opening area of ​​all the through holes 70 (opening rate) is preferably 20% or more and 60% or less, and more preferably 35% or more and 45% or less. Note that, although the arrangement of the through holes 70 is staggered in this embodiment, they may be arranged in other patterns (for example, a lattice pattern).

[0034] The area of ​​each through hole 70 is preferably 0.031 mm 2 More than 50.3mm 2 That is, when the hole shape is circular, the diameter is preferably 0.2 mm or more and 8 mm or less, and more preferably 0.9 mm or more and 3 mm or less. When the hole shape is other than circular, the diameter can be obtained by calculating the circle equivalent diameter.

[0035] Here, when the flat foil 40 has through holes 70, the brazing material disposed on one side of the flat foil 40 may flow through the through holes 70 to the other side of the flat foil during the vacuum heat treatment, forming a joint with the corrugated foil 30 or the outer tube 20. Although it is only minor, the formation of such a joint can strengthen the joint.

[0036] Examples will be given to demonstrate that the honeycomb unit of the present invention satisfies durability requirements. The flat foil 40 and the corrugated foil 30 were made of Fe-20Cr-5Al ferritic stainless steel with thicknesses of 30 μm, 40 μm, and 50 μm. The outer tube 20 was made of EN standard 1.4509 with thicknesses of 1.0 mm, 1.5 mm, and 2.0 mm. The brazing material was a Ni-based brazing material (BNi-5) with a thickness of 25 μm, and foil brazing material with widths of 1 mm, 3 mm, 5 mm, and 10 mm was used.

[0037] (First embodiment) Examples 1 to 44 corresponding to the first embodiment will be described. Two flat foils made of Fe-20Cr-5Al stainless steel with the same thickness were prepared, one of the flat foils was provided with Ni-based brazing material (BNi-5), and the other flat foil was processed into a corrugated foil. These flat foils and corrugated foils were overlapped and wound to produce a honeycomb body that had not been subjected to heat treatment. This honeycomb body that had not been subjected to heat treatment was inserted into an outer cylinder made of ferritic stainless steel of EN standard 1.4509, and heat-treated at 1200°C in a vacuum atmosphere to produce a honeycomb unit. The outer diameter, axial length, and thickness of the outer cylinder were appropriately set according to the diameter and axial length of the honeycomb body.

[0038] A washcoat layer mainly composed of ceria-zirconia-alumina was formed on the honeycomb unit. A washcoat liquid was passed through the honeycomb body, and after removing excess washcoat liquid, the honeycomb body was dried at 180°C for 1 hour, and then fired at 500°C for 2 hours, so that the washcoat layer was supported on the honeycomb body at a ratio of 180g / L per honeycomb body volume. The honeycomb body with this washcoat layer formed was immersed in an aqueous solution containing palladium. It was taken out and dried, so that 4g / L of palladium was supported per honeycomb unit volume.

[0039] The durability of the honeycomb unit was evaluated by a heating and cooling cycle test using a burner test device (not shown). The honeycomb unit was set in the burner test device, and the number of cooling and heating cycles until the phenomenon of the honeycomb body falling off from the outer cylinder (core displacement, etc.) occurred was examined. The gas piping from the burner and the outer cylinder were welded via a cone (not shown). The cooling and heating cycle pattern was a temperature pattern in which the inlet gas temperature of the honeycomb unit was repeatedly changed between 1000°C and 100°C. One cycle consisted of raising the inlet gas to 1000°C in 10 seconds, holding it for 1 minute, and then cooling it to 100°C in 30 seconds. Observation was continued for 1000 cycles, and if the honeycomb body did not fall off after 1000 cycles, it was evaluated as having excellent durability and passing.

[0040] Table 1 shows the parameters of each of the honeycomb units according to Examples 1 to 44. [Table 1]

[0041] In Examples 1 to 44, the inlet region was provided with the first bonding portion 61, the second bonding portion 62, and the third bonding portion 30. On the other hand, the outlet region was provided with the third bonding portion 30 and the first bonding portion 61. However, in Example 32, the third bonding portion 30 was not provided in the outlet region. Example 2 etc. corresponds to the arrangement shown in FIG. 2. Example 7 etc. corresponds to the arrangement shown in FIG. 3A. Example 20 etc. corresponds to the arrangement shown in FIG. 4. Example 28 etc. corresponds to the arrangement shown in FIG. 5. Example 32 etc. corresponds to the arrangement shown in FIG. 6. Example 30 etc. corresponds to the arrangement shown in FIG. 7. In all the examples, the durability was acceptable.

[0042] (Second Example) An explanation will be given of Examples 45 to 86 corresponding to the second embodiment. Table 2 shows the parameters of each honeycomb unit according to Examples 45 to 86. [Table 2] The honeycomb unit was the same as that in the first embodiment, except for the positions of the joints. In Examples 45 to 86, the first bonding portion 61, the second bonding portion 62, and the third bonding portion 30 were disposed in the inlet region. Meanwhile, the second bonding portion 62 was disposed in the outlet region. However, in Examples 73 and 74, the third bonding portion 30 was disposed together with the second bonding portion 62 in the outlet region. Example 46 etc. corresponds to the arrangement shown in Figure 9. Example 73 corresponds to the arrangement shown in Figure 8. In all the examples, the durability was acceptable.

[0043] In the above-mentioned first and second examples, through holes were formed in the flat foil and corrugated foil, and durability tests were conducted separately. Through holes were formed in the corrugated foil while it was in the flat foil state, and this was processed into corrugated foil. The width of the edge regions T1 and T2 was 5 mm. The shape of the through holes formed in the hole formation region D was a circle with a diameter of 0.9 mm. The opening ratio was set to 40%. In all examples, the durability was acceptable. [Explanation of symbols]

[0044] 1: Honeycomb unit 10: Honeycomb body 11: Gas inlet edge 12: Gas outlet edge 20: Outer cylinder 30: Wave foil 40: Flat foil 50: 3rd joint 60: Flat foil - corrugated foil joint 61: 1st joint 62:Second joint 70:Through hole

Claims

1. A honeycomb unit for purifying exhaust gases is formed by winding a honeycomb body made of flat metal foil and corrugated metal foil, and partially joining a metal outer cylinder surrounding the outer peripheral surface of the honeycomb body, A joint between a flat foil and a corrugated foil is defined as a first joint, a joint provided on an outer peripheral surface of the flat foil, and a second joint, a joint provided on an inner peripheral surface of the flat foil, When the joint between the honeycomb body and the outer cylinder is defined as the third joint, a first joint, a second joint and a third joint are disposed in an exhaust gas inlet region, one of the first joint, the second joint and the third joint is disposed at a position offset from the other two joints in the axial direction of the honeycomb body, and the other two joints are disposed at the same position or at offset positions from each other in the axial direction of the honeycomb body, A honeycomb unit characterized in that a first joint portion or a second joint portion is disposed in an exhaust gas outlet region.

2. 2. The honeycomb unit according to claim 1, further comprising a third joint portion disposed in an exhaust gas outlet region.

3. In the exhaust gas inlet region, the first bonding portion and the third bonding portion are disposed at the same position in the axial direction of the honeycomb body, and the second bonding portion is disposed at a position offset from the first bonding portion and the third bonding portion in the axial direction of the honeycomb body, 3. The honeycomb unit according to claim 1, wherein the first joint portion is not provided in the exhaust gas outlet region, but the second joint portion is provided.

4. 3. The honeycomb unit according to claim 1, wherein the flat foil and / or the corrugated foil has a plurality of through holes formed therein.

5. 4. The honeycomb unit according to claim 3, wherein the flat foil and / or the corrugated foil has a plurality of through holes formed therein.

6. A catalytic converter comprising the honeycomb unit according to claim 1 or 2, and a catalyst supported thereon.

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