Catalyst structure

Abstract

To provide a catalyst device capable of enhancing durability of a honeycomb core while maintaining purification performance of a combustion gas.SOLUTION: In a catalytic device (30) having a honeycomb core (31) formed by winding a metal foil (40) with a catalyst carried thereon, a plurality of through holes (H) is formed in part of the metal foil (40). In the flow direction of the combustion gas (G) that passes through the honeycomb core (31), they are arranged in the following order from the upstream side: a first region (A) where no through holes (H) are provided, a second region (B) where through holes (H) are provided, and a third region (C) where no through holes (H) are provided. When the flow direction of the combustion gas (G) is considered to be along the width direction, the width (TA) of the first region (A) is set to be smaller than the width (TC) of the third region (C). The metal foil (40) is composed of a flat foil (41) and a corrugated foil (42) stacked together, and a first brazing part (51) that joins the flat foil (41) and the corrugated foil (42) is provided at the upstream end of the honeycomb core (31).SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a catalytic converter, and more particularly to a catalytic converter having a honeycomb core formed by laminating metal foils carrying a catalyst. [Background technology]

[0002] 2. Description of the Related Art Conventionally, catalytic converters have been known that purify combustion gas from an internal combustion engine by passing the gas through a honeycomb core made of laminated metal foils carrying a catalyst such as platinum.

[0003] Patent Document 1 discloses a catalytic device in which multiple through holes are provided in the metal foil to suppress two phenomena that tend to occur when used at high temperatures: thermal strain caused by temperature differences inside the honeycomb core, and the phenomenon in which the oxide coating formed on the surface of the metal foil expands in volume, causing the metal foil itself to stretch. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5199291 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the honeycomb core in Patent Document 1 has through holes arranged in a checkerboard pattern throughout the entire metal foil, which causes large pressure fluctuations inside the catalytic device when combustion gas flows. This pressure fluctuation can cause deterioration of the brazed parts of the honeycomb core, posing the problem that measures were needed to address this issue.

[0006] An object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a catalytic converter capable of improving the durability of a honeycomb core while maintaining the purification performance of combustion gas. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention has a first feature in that a catalyst device (30) having a honeycomb core (31) formed by winding a metal foil (40) carrying a catalyst, in which a plurality of through holes (H) are formed in at least a portion of the metal foil (40), and in the flow direction of a combustion gas (G) passing through the honeycomb core (31), a first region (A) in which the through holes (H) are not provided, a second region (B) in which the through holes (H) are provided, and a third region (C) in which the through holes (H) are not provided are arranged in this order from the upstream side, and when the flow direction of the combustion gas (G) is taken as the width direction, the width (TA) of the first region (A) is set smaller than the width (TC) of the third region (C).

[0008] A second feature of the catalyst device (30) is that it has a honeycomb core (31) formed by winding a metal foil (40) carrying a catalyst, and a plurality of through holes (H) are formed in at least a portion of the metal foil (40). In the flow direction of a combustion gas (G) passing through the honeycomb core (31), a first region (A) in which the through holes (H) are not provided is provided from the upstream side, a second region (B) in which the through holes (H) are provided, and a third region (C) in which the through holes (H) are not provided is provided from the downstream side. When the flow direction of the combustion gas (G) is taken as the width direction, the width (TA) of the first region (A) is set smaller than the width (TC) of the third region (C).

[0009] In addition, the metal foil (40) is constructed by stacking a flat foil (41) and a corrugated foil (42), and a third feature is that a first brazing portion (51) joining the flat foil (41) and the corrugated foil (42) is provided at the upstream end of the honeycomb core (31).

[0010] The fourth feature is that no brazing is applied to the second region (B).

[0011] Furthermore, a fifth feature is that the catalytic converter (30) is provided with a second brazing portion (52) that joins the flat foil (41) and the corrugated foil (42) downstream of the first brazing portion (51), and a third brazing portion (53) that joins the honeycomb core (31) and an outer tube (32) that houses the honeycomb core (31), and the second brazing portion (52) and the third brazing portion (53) overlap each other in a side view of the catalytic converter (30).

[0012] A sixth feature is that the second brazed portion (52) and the third brazed portion (53) are provided at positions closer to the downstream side of the catalytic converter (30).

[0013] A seventh feature is that the width (T2) of the second brazed portion (52) is set smaller than the width (T3) of the third brazed portion (53).

[0014] An eighth feature is that the width (TB) of the second region (B) is set larger than the width (TC) of the third region (C). Effect of the Invention

[0015] According to a first feature, in a catalyst device (30) having a honeycomb core (31) formed by winding a metal foil (40) carrying a catalyst, a plurality of through holes (H) are formed in at least a part of the metal foil (40), and in the flow direction of a combustion gas (G) passing through the honeycomb core (31), a first region (A) in which the through holes (H) are not formed, a second region (B) in which the through holes (H) are formed, and a third region (C) in which the through holes (H) are not formed are arranged in this order from the upstream side, and when the flow direction of the combustion gas (G) is taken as the width direction, the width (TA) of the first region (A) is set smaller than the width (TC) of the third region (C). Therefore, compared to a configuration in which through holes are formed in the entire metal foil, it is possible to diffuse the combustion gas in the upstream first region in which no through holes are formed, and to prevent the internal pressure of the catalyst device from becoming too high. This makes it possible to increase the durability of the honeycomb core while maintaining the purification performance of the combustion gas.

[0016] According to a second feature, in a catalyst device (30) having a honeycomb core (31) formed by winding a metal foil (40) carrying a catalyst, a plurality of through holes (H) are formed in at least a part of the metal foil (40), and in the flow direction of a combustion gas (G) passing through the honeycomb core (31), a first region (A) in which the through holes (H) are not formed from the upstream side, a second region (B) in which the through holes (H) are formed, and a third region (C) in which the through holes (H) are not formed from the downstream side are formed, and when the flow direction of the combustion gas (G) is defined as the width direction, the width (TA) of the first region (A) is set smaller than the width (TC) of the third region (C). Therefore, compared to a configuration in which through holes are formed in the entire metal foil, it is possible to diffuse the combustion gas in the upstream first region in which no through holes are formed, and to prevent the internal pressure of the catalyst device from becoming too high. This makes it possible to increase the durability of the honeycomb core while maintaining the purification performance of the combustion gas.

[0017] According to a third feature, the metal foil (40) is constructed by stacking a flat foil (41) and a corrugated foil (42), and a first brazing portion (51) joining the flat foil (41) and the corrugated foil (42) is provided at the upstream end of the honeycomb core (31). This increases the joining strength of the upstream end where the combustion gas first hits, and makes it possible to suppress damage to the metal foil.

[0018] According to the fourth feature, since no brazing is applied to the second region (B), it is possible to avoid pressure fluctuations and stress concentration caused by brazing material entering the through holes, thereby improving the durability of the catalytic device.

[0019] According to a fifth feature, there is provided a second brazing portion (52) that joins the flat foil (41) and the corrugated foil (42) downstream of the first brazing portion (51), and a third brazing portion (53) that joins the honeycomb core (31) and an outer tube (32) that houses the honeycomb core (31). The second brazing portion (52) and the third brazing portion (53) overlap each other in a side view of the catalytic device (30). Therefore, the second brazing portion suppresses the thermal distortion phenomenon of the honeycomb core at a position near the downstream side of the catalytic device, thereby making it possible to suppress deformation of the outer tube and increase the durability of the third brazing portion.

[0020] According to the sixth feature, the second brazing portion (52) and the third brazing portion (53) are provided at a position closer to the downstream side of the catalytic device (30). By providing the second brazing portion and the third brazing portion at a position closer to the downstream side where the temperature is lower than the upstream side, the third brazing portion can be protected from thermal influences and the honeycomb core can be prevented from coming off the outer tube.

[0021] According to the seventh feature, the width (T2) of the second brazing portion (52) is set smaller than the width (T3) of the third brazing portion (53). Therefore, even if the third brazing portion is affected by a thermal strain phenomenon, the resulting stress is easily dispersed in the second brazing portion, making it possible to suppress the effect on the honeycomb core.

[0022] According to the eighth feature, the width (TB) of the second region (B) is set larger than the width (TC) of the third region (C). Therefore, by making the area of ​​the second region in which the through holes are provided sufficiently large, it is possible to maintain the purification performance of the catalytic converter. [Brief description of the drawings]

[0023] [Figure 1] 1 is a left side view of an exhaust system to which a catalytic converter according to an embodiment of the present invention is applied; [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Diagram 3] FIG. [Figure 4] FIG. 2 is a front view showing the structure of a honeycomb core. [Diagram 5] FIG. 2 is a partially enlarged perspective view showing the structure of a honeycomb core. [Figure 6] FIG. 2 is a schematic cross-sectional view showing the structure of a catalytic converter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a left side view of an exhaust system 1 to which a catalytic converter 30 according to one embodiment of the present invention is applied. The directional arrows in the drawing correspond to the direction of a vehicle, such as a motorcycle, to which the exhaust system 1 is attached.

[0025] The exhaust device 1 has an exhaust pipe 2 attached to a cylinder head of an internal combustion engine (not shown), a catalyst housing section 4 connected to the rear of the exhaust pipe 2, and a muffler 6 connected to the rear of the catalyst housing section 4. The catalyst housing section 4 and the muffler 6 are provided with plate-shaped stays 3, 5 for fixing the exhaust device 1 to a vehicle. Combustion gas G from the internal combustion engine is sent to the catalyst housing section 4 through the exhaust pipe 2, purified by a catalytic device 30 housed in the catalyst housing section 4, and then silenced by the muffler 6 and exhausted rearward.

[0026] Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a perspective view of the catalytic converter 30. The same reference numerals as those in the above-mentioned drawings indicate the same or equivalent parts as those in the above-mentioned drawings. In Fig. 2, the directional arrows "front" and "rear" correspond to the upstream side and downstream side of the combustion gas G, respectively.

[0027] The catalytic converter 30, which has a substantially cylindrical shape, has a cylindrical honeycomb core 31 housed in a cylindrical outer cylinder 32. A front tapered pipe 9 connected to the exhaust pipe 2 is connected to the front end of the outer cylinder 32. Meanwhile, a rear tapered pipe 11 connected to the tail pipe 12 is connected to the rear end of the outer cylinder 32. The radial outside of the outer cylinder 32 is wrapped with a heat insulating pipe 10 which constitutes the catalyst storage section 4, and the front end of the heat insulating pipe 10 is connected to the exhaust pipe 2 via an outer tapered pipe 8.

[0028] FIG. 4 is a front view showing the structure of the honeycomb core 31. The honeycomb core 31 has a honeycomb structure formed by winding a metal foil 40, which is made by overlapping flat foil 41 and corrugated foil 42 carrying a catalyst such as platinum, multiple times. The flat foil 41 and corrugated foil 42 can be made of ferritic stainless steel having a thickness of 30 to 100 μm, for example. The honeycomb core 31 is manufactured by overlapping the flat foil 41 and corrugated foil 42, in which a brazing material such as nickel brazing is placed at a predetermined position, to form the metal foil 40, and storing the wound metal foil 40 in the outer cylinder 32, which is heated in a vacuum furnace for vacuum brazing.

[0029] 5 is a partially enlarged perspective view showing the structure of the honeycomb core 31. The same reference numerals as those described above indicate the same or equivalent parts. The flat foil 41 and the corrugated foil 42 are joined to each other by brazing at the apexes of the peaks and valleys of the corrugated foil 42. A plurality of through holes H are formed in each of the flat foil 41 and the corrugated foil 42. The through holes H are provided to prevent a thermal strain phenomenon caused by a temperature difference inside the honeycomb core 31 and a phenomenon in which the metal foil 40 itself is stretched due to the volume expansion of an oxide film formed on the surface of the metal foil 40.

[0030] However, for example, providing the through holes H throughout the entire metal foil 40 increases the pressure fluctuations inside the catalytic device 30 when the combustion gas G flows, and this pressure fluctuation may deteriorate the brazed portions of the honeycomb core 31, posing the problem that measures are necessary. In response to this problem, the present invention intentionally provides areas where the through holes H are not provided, thereby making it possible to increase the durability of the honeycomb core 31 while maintaining the purification performance of the combustion gas G.

[0031] 6 is a schematic cross-sectional view showing the structure of the catalytic device 30. In the honeycomb core 31 according to this embodiment, a first region A where no through holes H are provided, a second region B where the through holes H are provided, and a third region C where no through holes H are provided are arranged in this order from the upstream side of the combustion gas G. In addition, when the flow direction of the combustion gas G is the width direction, the width TA of the first region A is set smaller than the width TC of the third region C.

[0032] This makes it possible to prevent the internal pressure of the catalytic device 30 from becoming too high by diffusing the combustion gas G in the upstream first region A where no through holes H are provided, as compared to a configuration in which the through holes H are formed in the entire metal foil 40. This makes it possible to improve the durability of the honeycomb core 31 while maintaining the purification performance of the combustion gas G.

[0033] The through holes H may be, for example, 33 rows of staggered circular holes each having a diameter of 2.2 mm. The through holes H may be reduced in diameter and increased in number, or may have a non-circular shape such as an ellipse. In this embodiment, the width TB of the second region B is set to about 1 / 2 of the overall width after considering the balance between purification performance and durability.

[0034] Furthermore, the present invention is characterized in that the first brazing portion 51 that joins the flat foil 41 and the corrugated foil 42 is provided at the upstream end of the honeycomb core 31. This increases the joining strength of the upstream end where the combustion gas G hits first, and makes it possible to suppress damage to the metal foil.

[0035] In addition, in this embodiment, no brazing is performed on the second region B in which the through hole H is provided. This makes it possible to avoid pressure fluctuations and stress concentration caused by the entry of brazing filler into the through hole H, and improves the durability of the catalytic device 30.

[0036] The catalytic device 30 includes a second brazing portion 52 that joins the flat foil 41 and the corrugated foil 42 at a position closer to the downstream side. The catalytic device 30 further includes a third brazing portion 53 that joins the honeycomb core 31 and the outer casing 32 that houses the honeycomb core 31. The present embodiment is characterized in that the second brazing portion 52 and the third brazing portion 53 overlap each other in a side view of the catalytic device 30. This makes it possible for the second brazing portion 52 to suppress the thermal distortion phenomenon of the honeycomb core 31 at a position closer to the downstream side of the catalytic device 30 and to suppress deformation of the outer casing 32, thereby increasing the durability of the third brazing portion 53.

[0037] The second brazed portion 52 and the third brazed portion 53 are provided at a position closer to the downstream side of the catalytic device 30. This prevents an excessive increase in temperature of the second brazed portion 52 and the third brazed portion 53, and in particular, prevents the honeycomb core 31 from coming off the outer casing 32 of the catalytic device 30 due to deterioration of the second brazed portion 52.

[0038] Moreover, the width T2 of the second brazed portion 52 is set smaller than the width T3 of the third brazed portion 53. As a result, even if the third brazed portion 53 is affected by a thermal strain phenomenon, the resulting stress is easily dispersed in the second brazed portion 52, making it possible to protect the honeycomb core 31. Furthermore, since the width TB of the second region B is set larger than the width TC of the third region C, the purification performance of the catalytic device 30 can be maintained by sufficiently increasing the area of ​​the second region B where the through holes H are provided.

[0039] In the above embodiment, the width TA of the first region A and the width T1 of the first brazing portion 51 are set to be the same, but the two widths may be different.

[0040] The form of the vehicle to which the exhaust device is attached, the shape and structure of the exhaust device, the shape and arrangement of the catalytic converter, the material of the flat foil and corrugated foil constituting the metal foil of the honeycomb core, the width of the first region, the second region, and the third region, the width and arrangement of the first brazed portion, the second brazed portion, and the third brazed portion, the shape and size of the through holes, the number of the through holes, and the like are not limited to the above-mentioned embodiment, and various modifications are possible. For example, the catalytic converter is not limited to a cylindrical shape, and may have an elliptical cross section, etc. In addition, in the above-mentioned embodiment, the first region without a through hole, the second region with a through hole, and the third region without a through hole are arranged in this order from the upstream side, but for example, between the second region and the third region, there may be a plurality of regions without a through hole and a plurality of regions with a through hole. The catalytic converter according to the present invention is not limited to motorcycles, but can be applied to exhaust devices of vehicles such as three-wheeled vehicles and four-wheeled vehicles, and various devices powered by internal combustion engines. [Explanation of symbols]

[0041] REFERENCE SIGNS LIST 1...exhaust device, 30...catalyst device, 31...honeycomb core, 32...outer tube, 40...metal foil, 41...flat foil, 42...corrugated foil, 51...first brazed portion, 52...second brazed portion, 53...third brazed portion, A...first region, B...second region, C...third region, TA...width of first region, TB...width of second region, TC...width of third region, T1...width of first brazed portion, T2...width of second brazed portion, T3...width of third brazed portion, H...through hole, G...combustion gas

Claims

1. A catalyst device (30) having a honeycomb core (31) formed by winding a metal foil (40) carrying a catalyst, A plurality of through holes (H) are formed in at least a portion of the metal foil (40), In a flow direction of a combustion gas (G) passing through the honeycomb core (31), a first region (A) in which the through holes (H) are not provided, a second region (B) in which the through holes (H) are provided, and a third region (C) in which the through holes (H) are not provided are arranged in this order from the upstream side, A catalytic converter, wherein the width (TA) of the first region (A) is set smaller than the width (TC) of the third region (C) when the flow direction of the combustion gas (G) is the width direction.

2. A catalyst device (30) having a honeycomb core (31) formed by winding a metal foil (40) carrying a catalyst, A plurality of through holes (H) are formed in at least a portion of the metal foil (40), In a flow direction of a combustion gas (G) passing through the honeycomb core (31), a first region (A) in which the through holes (H) are not provided, a second region (B) in which the through holes (H) are provided, and a third region (C) in which the through holes (H) are not provided, are provided from the upstream side. A catalytic converter, wherein the width (TA) of the first region (A) is set smaller than the width (TC) of the third region (C) when the flow direction of the combustion gas (G) is the width direction.

3. The metal foil (40) is constructed by overlapping a flat foil (41) and a corrugated foil (42), 3. The catalytic converter according to claim 1, wherein a first brazing portion (51) that joins the flat foil (41) and the corrugated foil (42) is provided at an upstream end of the honeycomb core (31).

4. 3. The catalytic converter according to claim 1, wherein the second region (B) is not brazed.

5. a second brazing portion (52) that joins the flat foil (41) and the corrugated foil (42) downstream of the first brazing portion (51); a third brazing portion (53) that joins the honeycomb core (31) and an outer cylinder (32) that houses the honeycomb core (31); The catalyst structure according to claim 3 , wherein the second brazed portion (52) and the third brazed portion (53) overlap each other in a side view of the catalyst device (30).

6. The catalytic converter according to claim 5, wherein the second brazed portion (52) and the third brazed portion (53) are provided at a position toward a downstream side of the catalytic converter (30).

7. 6. The catalytic converter according to claim 5, wherein a width (T2) of the second brazed portion (52) is set smaller than a width (T3) of the third brazed portion (53).

8. 3. The catalytic converter according to claim 1, wherein the width (TB) of the second region (B) is set to be larger than the width (TC) of the third region (C).

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