Catalyst device

Abstract

The problem addressed by the present invention is to provide a catalyst device capable of improving the durability of a honeycomb core while maintaining exhaust gas purification performance. In order to solve the problem, the present invention provides a catalyst device (30) in which exhaust gas (G) is purified by passing through a honeycomb core (31) in which a metal foil (40) on which a catalyst is supported is wound, a plurality of through-holes (H) are formed in a part of the metal foil (40), and the through-holes (H) are formed in a part of the metal foil (40) in the axial direction of the flow of the exhaust gas (G) in the honeycomb core (31). A boundary region (C) is provided between a dense region (A) in which the through-holes (H) are densely formed and a non-porous region (B) in which the through-holes (H) are not formed, and the boundary region (C) is configured such that the total area of the through-holes (H) gradually decreases from the dense region (A) side toward the non-porous region (B) side. The boundary region (C) is provided only on the downstream side of the exhaust gas (G) with respect to the dense region (A).

Description

Technical Field

[0001] This invention relates to a catalyst device, and more particularly to a catalyst device having a honeycomb core formed by stacking metal foils carrying a catalyst. Background Technology

[0002] In the past, efforts have been made to mitigate climate change or reduce its impacts, and research and development related to improving emissions is underway to achieve this goal. Here, it is known that honeycomb cores are used in catalyst devices for purifying exhaust gases from internal combustion engines; these honeycomb cores are made by stacking metal foils carrying catalysts such as platinum.

[0003] Patent Document 1 discloses a catalyst device in which multiple through holes are provided on the metal foil constituting the honeycomb core to increase the surface area of ​​the honeycomb core. In addition, it suppresses thermal strain caused by internal temperature difference and elongation of the metal foil caused by volume expansion of the acidified film formed on the surface of the metal foil.

[0004] [Previous Technical Documents]

[0005] (Patent Documents)

[0006] Patent Document 1: Japanese Patent No. 5199291 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, the honeycomb core of Patent Document 1 has the following problem: since the area with densely arranged through holes in the same pattern as the checkerboard grid is connected to the area with no through holes at all, a difference in the strength of the metal foil is generated at the boundary, and a way needs to be found to maintain the durability of the honeycomb core.

[0009] The object of this invention is to provide a catalyst device that solves the problems of the prior art described above, wherein the catalyst device can maintain the purification performance of exhaust gas and improve the durability of the honeycomb core. Furthermore, this helps to mitigate climate change or reduce its impact.

[0010] [Technical means to solve the problem]

[0011] To achieve the aforementioned objective, the first feature of the present invention is a catalyst device (30) that purifies waste gas (G) by passing it through a honeycomb core (31), wherein the honeycomb core (31) is formed by winding a metal foil (40) carrying a catalyst, and a plurality of through holes (H) are formed on a portion of the metal foil (40). In the axial direction of the flow of the aforementioned waste gas (G) in the aforementioned honeycomb core (31, 31a, 31b, 31c, 31d), a boundary region (C) is provided between a dense region (A) where the aforementioned through holes (H) are densely formed and a non-porous region (B) where the aforementioned through holes (H) are not formed. The boundary region (C) is configured such that the total area of ​​the aforementioned through holes (H) gradually decreases from the dense region (A) side to the non-porous region (B) side.

[0012] Furthermore, the second feature is that the aforementioned boundary region (C) is located only downstream of the aforementioned dense region (A) from the aforementioned exhaust gas (G).

[0013] Furthermore, the third feature is that the aforementioned boundary region (C) is configured to reduce the number of the aforementioned through holes (H), thereby gradually reducing the total area of ​​the aforementioned through holes (H).

[0014] Furthermore, the fourth feature is that the aforementioned through holes (H) are arranged with the same diameter and at equal intervals in the aforementioned dense region (A), and the aforementioned boundary region (C) is configured such that, while maintaining the arrangement of the aforementioned through holes (H) in the aforementioned dense region (A), the aperture of the aforementioned through holes (H) gradually decreases, thereby gradually reducing the total area of ​​the aforementioned through holes (H).

[0015] Furthermore, the fifth feature is that the aforementioned through holes (H) are arranged with the same diameter and at equal intervals in the aforementioned dense region (A), and the aforementioned boundary region (C) is configured such that, while maintaining the arrangement of the aforementioned through holes (H) in the aforementioned dense region (A), the number of the aforementioned through holes (H) is reduced, thereby gradually reducing the total area of ​​the aforementioned through holes (H), and no aforementioned through holes (H) are formed around the aforementioned through hole (H) at the position closest to the aforementioned non-hole region (B).

[0016] Furthermore, the sixth feature is that the aforementioned boundary region (C) is located on both the upstream and downstream sides of the aforementioned dense region (A) relative to the aforementioned exhaust gas (G).

[0017] (The effect of the invention)

[0018] According to the first feature, the catalyst device (30) purifies the waste gas (G) by passing it through a honeycomb core (31), which is formed by winding a metal foil (40) carrying a catalyst. A plurality of through holes (H) are formed on a portion of the metal foil (40). In the axial direction of the flow of the waste gas (G) in the honeycomb core (31, 31a, 31b, 31c, 31d), a boundary region (C) is provided between a dense region (A) where the through holes (H) are densely formed and a non-porous region (B) where the through holes (H) are not formed. The boundary region (C) is configured such that the total area of ​​the through holes (H) gradually decreases from the dense region (A) side to the non-porous region (B) side. Therefore, by providing a boundary region between the dense region and the non-porous region, compared with the configuration where the dense region and the non-porous region are connected, the strength reduction of the switching part between the dense region and the non-porous region can be suppressed, thereby improving the durability of the honeycomb core.

[0019] According to the second feature, since the aforementioned dense region (A) is only located downstream of the aforementioned exhaust gas (G), the exhaust gas can be diffused within the dense region to improve purification efficiency and suppress the reduction in the strength of the honeycomb core in the boundary region.

[0020] According to the third feature, the aforementioned boundary region (C) is configured to reduce the number of the aforementioned through holes (H), thereby gradually reducing the total area of ​​the aforementioned through holes (H), thus reducing the number of processing pins used to form through holes in the honeycomb core.

[0021] According to the fourth feature, the aforementioned through holes (H) are arranged with the same diameter and at equal intervals in the aforementioned dense region (A). The aforementioned boundary region (C) is configured such that, while maintaining the arrangement of the aforementioned through holes (H) in the aforementioned dense region (A), the aperture of the aforementioned through holes (H) is gradually reduced, thereby gradually reducing the total area of ​​the aforementioned through holes (H). Therefore, the diffusion effect achieved by the through holes can be maintained, and the strength reduction of the honeycomb core in the boundary region can be suppressed.

[0022] According to the fifth feature, the aforementioned through holes (H) are arranged with the same diameter and at equal intervals in the aforementioned dense region (A). The aforementioned boundary region (C) is configured such that, while maintaining the arrangement of the aforementioned through holes (H) in the aforementioned dense region (A), the number of the aforementioned through holes (H) is reduced, thereby gradually reducing the total area of ​​the aforementioned through holes (H). The aforementioned through holes (H) are not formed around the aforementioned through holes (H) at the position closest to the aforementioned non-porous region (B). Therefore, by not setting through holes around the through holes at the position closest to the non-porous region, the strength reduction of the honeycomb core in the boundary region can be suppressed.

[0023] According to the sixth feature, the aforementioned boundary region (C) is located on both the upstream and downstream sides of the aforementioned dense region (A) of the aforementioned exhaust gas (G). Therefore, the strength reduction of the honeycomb core in the boundary region can be suppressed on the upstream and downstream sides of the dense region. Attached Figure Description

[0024] Figure 1 This is a left-side view of the exhaust device of a catalyst device applying an embodiment of the present invention.

[0025] Figure 2 yes Figure 1 Sectional view of line II-II.

[0026] Figure 3 This is a three-dimensional view of the catalyst unit.

[0027] Figure 4 This is a front view showing the construction of the honeycomb core.

[0028] Figure 5 This is a partially enlarged perspective view showing the structure of the honeycomb core.

[0029] Figure 6 This is a side view of a honeycomb core 31 according to an embodiment of the present invention.

[0030] Figure 7 This is a side view of the honeycomb core of the first variation of this embodiment.

[0031] Figure 8 This is a side view of the honeycomb core of the second variation of this embodiment.

[0032] Figure 9 This is a side view of the honeycomb core in the third variation of this embodiment.

[0033] Figure 10 This is a partially enlarged side view of the honeycomb core of the fourth variation of this embodiment. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 This is a left-side view of an exhaust system 1 using a catalyst device 30 according to an embodiment of the present invention. The directional arrows in the figure correspond to the direction of the vehicle, such as a motorcycle, on which the exhaust system 1 is installed.

[0035] The exhaust system 1 includes an exhaust pipe 2 mounted on the cylinder head of an internal combustion engine (not shown), a catalyst housing 4 connected to the rear of the exhaust pipe 2, and a muffler 6 connected to the rear of the catalyst housing 4. Plate-shaped support rods 3 and 5 for fixing the exhaust system 1 to the vehicle are provided on the catalyst housing 4 and the muffler 6. The exhaust gas G from the internal combustion engine is sent to the catalyst housing 4 through the exhaust pipe 2, purified by the catalyst device 30 housed in the catalyst housing 4, and then silenced by the muffler 6 before being discharged to the rear.

[0036] Figure 2 yes Figure 1 The cross-sectional view along line II-II. Furthermore... Figure 3 This is a perspective view of the catalyst device 30. The same symbols as described above denote the same or equivalent parts. Figure 2 In the diagram, the "forward" and "backward" directions of the arrows correspond to the upstream and downstream sides of the exhaust gas G, respectively.

[0037] The generally cylindrical catalyst device 30 is configured such that a cylindrical honeycomb core 31 is housed within a cylindrical outer cylinder 32. A front conical pipe 9, connected to the exhaust pipe 2, is connected to the front end of the outer cylinder 32. Conversely, a rear conical pipe 11, connected to the tailpipe 12, is connected to the rear end of the outer cylinder 32. A heat insulation pipe 10, constituting the catalyst housing 4, is wound radially outward around the outer cylinder 32, and the front end of the heat insulation pipe 10 is connected to the exhaust pipe 2 via an outer conical pipe 8.

[0038] Figure 4 This is a front view showing the structure of the honeycomb core 31. The honeycomb core 31 is a core with a honeycomb structure formed by repeatedly winding a metal foil 40. The metal foil 40 is formed by overlapping flat foil 41 and corrugated foil 42 carrying a catalyst such as platinum. The flat foil 41 and corrugated foil 42 can be formed, for example, from ferritic stainless steel with a thickness of 30 to 100 μm. The honeycomb core 31 is manufactured by overlapping flat foil 41 and corrugated foil 42, which have brazing material such as nickel wax placed in specific positions, to form the metal foil 40. The metal foil 40 is then wound and placed in an outer cylinder 32, and vacuum brazed in a vacuum furnace.

[0039] Figure 5This is a partially enlarged perspective view showing the structure of the honeycomb core 31. The same symbols as above denote the same or equivalent parts. The flat foil 41 and the corrugated foil 42 are joined together by brazing at the apexes of the crests and troughs of the corrugated foil 42. Multiple through-holes H are formed on both the flat foil 41 and the corrugated foil 42. These through-holes H are provided to prevent thermal strain caused by temperature differences inside the honeycomb core 31 and to prevent the metal foil 40 from elongating due to volume expansion of the oxide film formed on the surface of the metal foil 40. Furthermore, this structure increases the surface area of ​​the catalyst in contact with the exhaust gas, thereby contributing to improved purification efficiency.

[0040] Here, the following problem exists: for example, when a region configured with densely packed through-holes H is adjacent to a region without any through-holes H, a strength difference in the metal foil 40 occurs at the boundary between the two regions, requiring a way to maintain the durability of the honeycomb core 31. To address this problem, the present invention is characterized by providing a boundary region C between the densely packed region with through-holes H and the non-porous region without through-holes H, and in this boundary region C, the total area of ​​the through-holes H gradually decreases from the densely packed region side to the non-porous region side, thereby improving the strength of the transition portion between the densely packed region and the non-porous region, and thus improving the durability of the honeycomb core.

[0041] Figure 6 This is a side view of a honeycomb core 31 according to an embodiment of the present invention. In this embodiment, on the cylindrical honeycomb core 31, in the axial direction of the flow of exhaust gas G, there is a dense region A with densely formed through holes H, a non-porous region B without through holes H, and a boundary region C disposed downstream of the dense region A between the dense region A and the non-porous region B. Multiple through holes H are arranged in the dense region A with the same diameter and at equal intervals. Furthermore, in the boundary region C, the total area of ​​the through holes H gradually decreases from the dense region A side to the non-porous region B side.

[0042] More specifically, in the boundary region C, the number of through holes H is reduced, thereby gradually decreasing the total area of ​​the through holes H. As a result, compared to a configuration where the dense region A connects to the non-porous region B, the strength reduction at the transition between the dense region A and the non-porous region B can be suppressed, thereby improving the durability of the honeycomb core 31. Furthermore, since the boundary region C is only located downstream of the exhaust gas G relative to the dense region A, the exhaust gas G can diffuse within the dense region A, improving purification efficiency and increasing the strength of the honeycomb core 31 within the boundary region C. By reducing the number of through holes H and thus gradually decreasing the total area of ​​the through holes H, the number of processing pins used to form the through holes H on the honeycomb core 31 can be reduced.

[0043] Furthermore, in this embodiment, in the boundary region C, while maintaining the configuration of through-holes H in the dense region A, the number of through-holes H is reduced, thereby gradually decreasing the total area of ​​the through-holes H, and no through-holes H are provided around the through-holes H closest to the holeless region B. This further enhances the strength of the honeycomb core 31 within the boundary region C.

[0044] Figure 7 This is a side view of the honeycomb core 31a of the first variation of this embodiment. In this first variation, the method for reducing the through-holes H in the boundary region C is the same as... Figure 6 The implementation methods shown are different. There can be various variations in the method of reducing the through hole H, such as reducing it one by one, or reducing two adjacent ones, etc.

[0045] Figure 8 This is a side view of the honeycomb core 31b in the second variation of this embodiment. In this second variation, the method for reducing the through-holes H within the boundary region C is also different. Figure 6 The implementation methods shown are as follows: Figure 7 The first variation shown is different. This second variation is a type in which no through-hole H is provided around the through-hole H at the position closest to the hole-free region B. There are various variations in the method of reducing through-hole H, such as linearly increasing the reduction amount for each row from upstream to downstream when the rows shown in the figure are set as through-hole H in the left and right direction, or gradually increasing the reduction amount for every two rows, etc.

[0046] Figure 9 This is a side view of the honeycomb core 31c in the third variation of this embodiment. In this third variation, the boundary region C is provided on both the upstream and downstream sides of the dense region A relative to the exhaust gas G. Therefore, the strength of the honeycomb core 31c within the boundary region C can be increased on both the upstream and downstream sides of the dense region A.

[0047] Figure 10 This is a partially enlarged side view of the honeycomb core 31d in the fourth variation of this embodiment. In this fourth variation, the boundary region C is configured such that, while maintaining the arrangement of the through holes H in the dense region A, the apertures (H1, H2, H3) of the through holes H gradually decrease, thereby gradually reducing the total area of ​​the through holes H. This allows for the improvement of the strength of the honeycomb core 31d within the boundary region C while maintaining the diffusion effect achieved by the through holes H. In this variation, the through holes H are arranged in the dense region A with the same diameter and at equal intervals, but the arrangement of the through holes H in the dense region A can also be varied. Furthermore, the aperture reduction pattern can be linearly reduced for each row, or, for example, gradually reduced for every two rows.

[0048] The form of the vehicle on which the exhaust system is installed, the shape or structure of the exhaust system, the shape or arrangement of the catalyst device, the material of the flat foil or corrugated foil constituting the honeycomb core, the shape or structure of the honeycomb core, the pattern of the through holes, the shape or size of the through holes, and the number of through holes are not limited to the above embodiments and can be modified in various ways. For example, the catalyst device is not limited to a cylindrical shape, but can also be a shape with an elliptical cross-section. The catalyst device of the present invention is not limited to motorcycles, but can also be applied to exhaust systems of vehicles such as tricycles or four-wheeled vehicles, and various devices powered by internal combustion engines.

[0049] Figure Labels

[0050] 1. Exhaust device

[0051] 30 catalyst unit

[0052] 31, 31a, 31b, 31c, 31d honeycomb cores

[0053] 32 outer cylinder

[0054] 40 metal foil

[0055] 41 flat foil

[0056] 42 Corrugated Foil

[0057] A dense area

[0058] B Non-porous area

[0059] C Boundary Area

[0060] H-hole

[0061] G exhaust gas

Claims

1. A catalyst device for purifying exhaust gas (G) by passing through a honeycomb core (31, 31a, 31b, 31c, 31d) that is wound by a metal foil (40) on which a catalyst is supported, characterized in that, a plurality of through-holes (H) are formed on a portion of the aforementioned metal foil (40), in the axis direction of the aforementioned exhaust gas (G) flowing through the aforementioned honeycomb core (31, 31a, 31b, 31c, 31d), a boundary region (C) is provided between a dense region (A) in which the aforementioned through-holes (H) are densely formed and a non-hole region (B) in which the aforementioned through-holes (H) are not formed, and the aforementioned boundary region (C) is configured so that the total area of the aforementioned through-holes (H) gradually decreases from the aforementioned dense region (A) side to the aforementioned non-hole region (B) side. The aforementioned boundary region (C) is provided only on the downstream side of the aforementioned exhaust gas (G) with respect to the aforementioned dense region (A). The aforementioned boundary region (C) is configured so that the number of the aforementioned through-holes (H) is reduced, thereby gradually decreasing the total area of the aforementioned through-holes (H). The aforementioned through-holes (H) are arranged at the same diameter and at equal intervals from each other in the aforementioned dense region (A). The aforementioned boundary region (C) is configured so that the arrangement of the aforementioned through-holes (H) in the aforementioned dense region (A) is maintained, and the hole diameter of the aforementioned through-holes (H) is gradually reduced, thereby gradually decreasing the total area of the aforementioned through-holes (H).

2. The catalyst device of claim 1, wherein, The aforementioned through-holes (H) are arranged at the same diameter and at equal intervals from each other in the aforementioned dense region (A).

3. The catalyst device of claim 1 or 2, wherein, The aforementioned boundary region (C) is configured so that the arrangement of the aforementioned through-holes (H) in the aforementioned dense region (A) is maintained, and the aforementioned through-holes (H) are reduced, thereby gradually decreasing the total area of the aforementioned through-holes (H).

4. The catalyst device of claim 1 or 2, wherein, The aforementioned through-holes (H) are not formed around the aforementioned through-holes (H) at a position closest to the aforementioned non-hole region (B). The aforementioned boundary region (C) is provided on both the upstream side and the downstream side of the aforementioned exhaust gas (G) with respect to the aforementioned dense region (A).

5. The catalyst device of claim 3, wherein, ​ ​ ​ 6. The catalyst device of claim 1, wherein, ​

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