Exhaust purification device

Abstract

This exhaust gas purification device is provided with: a protruding section that forms a gas flow path by protruding a strip-shaped sheet section, which is divided by cutting sections at both front and rear locations in the longitudinal direction of a metal plate, toward the front surface side of the metal plate; and recessed portions which are recessed toward the back surface side by other belt-shaped sheet portions divided by other front and rear cutting portions and which form gas flow paths, the portions divided by the cutting portions form through holes, and the protruding portions and the recessed portions are alternately formed side by side across predetermined flat-plate-shaped connecting portions in at least either the longitudinal direction or the transverse direction. A plurality of metal plates, each of which has a catalyst attached to a front surface side and a rear surface side including a convex portion and a concave portion, are stacked such that the convex portions and the concave portions are offset from each other in the transverse direction, and the metal plates adjacent to each other in the stacking direction are joined at least by a connecting portion and connected.

Description

Technical Field

[0001] This invention relates to an apparatus for purifying exhaust gas by loading a catalyst onto a substrate and allowing exhaust gas to flow along the substrate, and more particularly to a structure of a substrate for loading a catalyst. Background Technology

[0002] The exhaust gas produced in a vehicle's internal combustion engine contains pollutants such as carbon monoxide (CO) or hydrocarbons (HC). Catalyst converters, which oxidize or reduce these pollutants to render them harmless, are integrated into the engine's exhaust system. To use a catalyst to purify the exhaust, active contact between the exhaust and the catalyst is necessary; various structures have been proposed for this purpose in the past.

[0003] Japanese Patent Application Publication No. 11-290699 discloses a honeycomb catalyst for flue gas denitrification. The honeycomb catalyst is mainly composed of a honeycomb structure supporting the catalyst, and multiple pores formed inside this honeycomb structure form gas flow paths. If the gas flow path is long, a boundary film grows along the inner surface of the pores, increasing the diffusion resistance of the exhaust gas to the catalyst. Therefore, in the honeycomb catalyst described in Japanese Patent Application Publication No. 11-290699, multiple slits spaced 300 mm or less are provided so that the gas flows laterally through the gas flow path.

[0004] Furthermore, Japanese Patent Application Publication No. 2007-511699 discloses an exhaust gas purification converter for internal combustion engines that uses a panel made of metal fibers carrying a catalyst. In the exhaust gas purification converter disclosed in Japanese Patent Application Publication No. 2007-511699, metal plates are sandwiched between panels to form a stack, and multiple stacks are stacked and housed in a housing. In each stack, exhaust gas flows between the panels and through the panels, thereby contacting the catalyst and purifying the exhaust gas. To ensure this exhaust gas flow path, a wing protruding towards one side of the metal plate is provided. The wing is, for example, a bent piece formed by cutting a portion of the metal plate along three sides of a rectangle, and bending it at the remaining side of the rectangle to protrude towards one side of the metal plate. Furthermore, a hole is formed in this rectangular portion. Summary of the Invention

[0005] In addition to handling high-temperature exhaust gases, exhaust purification devices also generate oxidation or reduction reactions of pollutants in the exhaust, sometimes resulting in high temperatures due to the heat generated by these reactions. Furthermore, devices mounted on vehicles are subject to significant vibrations caused by vehicle movement. Exhaust purification devices are inevitably subjected to such thermal stress or external forces. Therefore, in the configuration disclosed in Japanese Patent Application Publication No. 11-290699, for example, the honeycomb structure is interrupted at the slits, resulting in weak strength in those sections. Consequently, the honeycomb structure deforms or displaces due to thermal stress or vibration, leading to friction, contact, or collision between the honeycomb structures, which may cause damage to the honeycomb structure.

[0006] On the other hand, in the exhaust gas purification converter described in Japanese Patent Application Publication No. 2007-511699, purification is achieved by allowing exhaust gas to flow laterally through a panel made of metal fibers carrying a catalyst, thereby bringing the exhaust gas into contact with the catalyst. However, since the panel is arranged in a direction parallel to the exhaust gas flow direction, it is desirable to distribute the exhaust gas across the entire surface of the panel. Therefore, metal plates are placed between the panels, and wings are provided as spacers. That is, in the exhaust gas purification converter described in Japanese Patent Application Publication No. 2007-511699, the metal plates are components used to ensure the spacing between the panels and do not specifically perform the function of purifying the exhaust gas. Therefore, in the exhaust gas purification converter disclosed in Japanese Patent Application Publication No. 2007-511699, the number of constituent parts increases, potentially leading to a larger overall device size. In particular, the number of metal plates increases with the number of stacked sheets, thus increasing weight and potentially leading to higher costs.

[0007] The present invention was made in view of the above-mentioned technical problems, and its purpose is to provide an exhaust purification device that can reduce the number of required components, has excellent strength, and thus can fully ensure the flow path of exhaust gas and improve the exhaust purification efficiency.

[0008] To achieve the above objective, the present invention provides an exhaust gas purification device that purifies the exhaust gas generated by combustion by allowing it to flow along a metal plate, which serves as a substrate carrying a catalyst. The exhaust gas purification device is characterized by having: a protrusion, which is formed by a strip-shaped portion of the metal plate, divided by cut-off portions at two points along the longitudinal direction of the exhaust gas flow, bent or flexed towards one side of the metal plate to form a protruding gas flow path; and a recess, which is formed by other strip-shaped portions of the metal plate, divided by cut-off portions at other points along the longitudinal direction of the exhaust gas flow, towards the surface of the metal plate. The other side, i.e. the back side, is bent or folded to form a recessed gas flow path, and the portion divided by the cut-off portion becomes a through hole. The convex and the concave are alternately formed side by side in at least one of the longitudinal direction and the transverse direction orthogonal to the longitudinal direction, separated by a plate-shaped connecting portion. The catalyst is attached to a plurality of metal plates on the surface side and the back side including the convex and the concave, and the convex and the concave are stacked in such a way that the convex and the concave are staggered from each other in the transverse direction. Adjacent metal plates in the stacking direction are connected at least by the plate-shaped connecting portion.

[0009] In this invention, the top surface of the protrusion engages with the flat connecting portion of the other metal plates located on the upper side in the stacking direction, and the bottom surface of the concave portion engages with the flat connecting portion of the other metal plates located on the lower side in the stacking direction.

[0010] In this invention, the protrusions and concave portions are arranged alternately side by side in the transverse direction and alternately arranged in the longitudinal direction, and are staggered from each other in the transverse direction.

[0011] In this invention, the protrusions are arranged in multiple rows in the transverse direction in the metal plate, and the concave portions are arranged in the transverse direction between the rows of protrusions.

[0012] In this invention, the length of the connecting portion in the longitudinal direction is a predetermined length with an upper limit of length Le determined by the following formula, and the lengths of the protrusion and the recess in the longitudinal direction are a predetermined length with an upper limit of half of length Le determined by the following formula.

[0013] Le = {dH / 9.28 × √(ρ·u / μ)} 2

[0014] dH: hydraulic diameter (m), ρ: gas density (kg / m³) 3 u: gas velocity (m / s), μ: gas viscosity (Pas).

[0015] In this invention, a metal plate serving as the substrate carries a catalyst, thereby purifying the exhaust gas by contacting the catalyst as it flows along the surface and back of the metal plate. Specifically, recesses and protrusions penetrate in the longitudinal direction of the exhaust flow, forming a gas flow path. These protrusions or recesses are arranged in the longitudinal direction of the exhaust flow but are alternately staggered in the transverse direction, thus interrupting the gas flow path at the transversely staggered locations. That is, the gas flow path becomes a short flow path equivalent to the interval between the cut-off portions dividing the protrusions or recesses, or the width of the strip-shaped portion. Therefore, a flow path less susceptible to the diffusion resistance of the boundary film can be constructed, thereby improving the exhaust gas purification efficiency. Furthermore, since multiple catalyst-carrying metal plates are stacked, strength in the stacking direction can be ensured, and since they are fixed inside a predetermined housing or outer shell in the stacked state, transverse strength can be ensured. Moreover, since the protrusions or recesses arranged in the longitudinal direction are staggered relative to each other in the transverse direction, in the longitudinal direction, the protrusions or recesses engage with each other to prevent movement of the metal plates, thereby ensuring longitudinal strength. As a result, even when subjected to external forces such as thermal deformation or vibration, damage to the catalyst-carrying metal plate can be avoided or suppressed. Furthermore, a flat plate-shaped connecting portion is provided between the protrusions or recesses, and the top surface of the protrusion or the bottom surface of the recess is joined to this connecting portion, thereby connecting the stacked metal plates together. Therefore, the metal plate used to form the flow path also functions as the metal plate connecting the metal plates. Consequently, the number or variety of required components is reduced, simplifying the structure and reducing weight, thereby achieving cost reduction. Attached Figure Description

[0016] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements.

[0017] Figure 1 This is a schematic cross-sectional view showing the internal structure of the exhaust purification device in an embodiment of the present invention, with the casing cut open.

[0018] Figure 2 This is an enlarged cross-sectional view of a portion of the metal plate.

[0019] Figure 3 It is a three-dimensional view representing a portion of a metal plate.

[0020] Figure 4 This is an end view of the metal plate when it is cut in a transverse plane.

[0021] Figure 5 It is along Figure 3 End face view when the VV line is cut.

[0022] Figure 6It is an end face view showing the shape of the end face when two metal plates are stacked and cut along a transverse plane in this state.

[0023] Figure 7 It is a cross-sectional view showing the end face of two stacked metal plates cut along a transverse plane and other protrusions or recesses arranged in the longitudinal direction.

[0024] Figure 8 This refers to other stacking methods of metal plates. Figure 6 Same end face view.

[0025] Figure 9 It is a three-dimensional drawing representing other arrangements of protrusions and recesses in a metal plate. Detailed Implementation

[0026] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments described below are merely examples of implementing the present invention and do not limit the scope of the invention.

[0027] Figure 1 An example of an embodiment of the present invention is shown below. Figure 1 This is a schematic cross-sectional view showing the internal structure of the exhaust purification device 1 by cutting through the housing 2. The housing 2 has conical portions 4 and 5 integrally formed on the front and rear sides of the cylindrical portion 3. An inlet pipe 6 is provided on one conical portion 4, and an outlet pipe 7 is provided on the other conical portion 5. This exhaust purification device 1 is assembled into the exhaust system of an internal combustion engine (not shown) for use. It purifies the exhaust gas G generated by combustion by introducing it through the inlet pipe 6 and discharging it through the outlet pipe 7 towards a filter (not shown).

[0028] A catalyst unit 8 is housed inside the cylindrical section 3. The catalyst unit 8 is constructed by stacking multiple metal plates 9, which are fastened together and fixed to the inner surface of the cylindrical section 3. Figure 2 As shown in the enlarged view, the metal plate 9 is constructed by supporting the catalyst 10 on both its surface and back side, thus becoming a so-called catalyst substrate. Furthermore, in the following description, the metal plate 9 is sometimes referred to as the "catalyst".

[0029] The metal plate 9 has multiple protrusions 11 and recesses 12 that form a gas flow path P through which the exhaust gas G flows. Furthermore, in the following description, the portion protruding upwards in the accompanying drawings is designated as the protrusion 11, and the portion recessed downwards is designated as the recess 12. Also, the upper surface in the accompanying drawings is designated as the surface of the metal plate 9, and the lower surface is designated as the back surface of the metal plate 9. Figures 3 to 5 The image shows a metal plate 9 with protrusions 11 and recesses 12. Figure 3This is a perspective view showing a portion of metal plate 9. The direction indicated by the arrow is the direction of exhaust gas G flow, which is set as the longitudinal direction. Therefore, the direction orthogonal to the longitudinal direction on the surface of metal plate 9 is set as the transverse direction. Figure 4 This is an end view showing a cut along a transverse plane. Figure 5 This is an end view of a cut along a longitudinal plane.

[0030] In these Figures 3 to 5 In the metal plate 9 shown, protrusions 11 and recesses 12 are arranged alternately in the transverse direction. A predetermined interval is provided between these protrusions 11 and recesses 12, and the portions between them form a flat plate-shaped connecting portion 13. Furthermore, the protrusions 11 and recesses 12 are arranged in the longitudinal direction, but are staggered relative to each other in the transverse direction. The staggering method is arbitrary. Figures 3 to 5 In the example shown, the longitudinally adjacent protrusions 11 and concave portions 12 are staggered without overlapping in the longitudinal direction. More specifically, they are staggered sequentially in units of length of the protrusions 11 and concave portions 12 in the transverse direction.

[0031] Here, the longitudinal lengths of the protrusion 11 and the recess 12 will be explained. As described later, the protrusion 11 and the recess 12 form the gas flow path P, and similarly, a portion of the connecting portion 13 also forms the gas flow path. The length of the gas flow path P can be appropriately set, for example, based on pressure loss or the purification efficiency of the exhaust gas G. Furthermore, the longitudinal lengths of the protrusion 11 and the recess 12 can also be set considering the boundary film diffusion resistance. The boundary film within the gas flow path begins to grow from a predetermined position at the inlet of the gas flow path, and eventually the thickness of the boundary film reaches half the inner diameter or width of the gas flow path, resulting in a state where gas diffusion to the inner surface of the gas flow path is greatly hindered. The length Le from the inlet, up to half the inner diameter or width of the gas flow path, is expressed by the following formula.

[0032] (Equation 1)

[0033]

[0034] Here, dH is the hydraulic diameter (m) and ρ is the gas density (kg / m³). 3 ), u is the gas velocity (m / s), and μ is the gas viscosity (Pas).

[0035] As described above, since the protrusions 11 and concave portions 12 are arranged longitudinally, the longest portion of the aforementioned flat connecting portion 13 in the longitudinal direction is the sum of the lengths of the protrusions 11 and the concave portions 12, which is twice the length of either the protrusion or the concave portion 12 in the longitudinal direction. Therefore, considering that the longest portion of this connecting portion 13 also forms a gas flow path, the length of this portion is set to the length Le obtained from the above formula. Consequently, the length L of the protrusions 11 and the concave portions 12 in the longitudinal direction is set to "Le / 2".

[0036] The protrusion 11 and the recess 12 are not particularly limited, but are formed by deforming a portion of the metal plate 9. For example, two parallel cut-out portions 14 are provided on the metal plate 9 facing laterally, and the portion between these cut-out portions 14, i.e., the strip-shaped portion 15, protrudes towards the surface side of the metal plate 9 to form the protrusion 11, and is recessed towards the back side to form the recess 12. As a result, the portion where the strip-shaped portion 15 moves out becomes the through hole 16. In addition, the shapes of the protrusion 11 and the recess 12 can be any shapes that form a flow path by penetrating longitudinally, and can be set to appropriate shapes as needed. Figures 3 to 5 In the example shown, the convex portion 11 and the concave portion 12 are in different vertical directions, but have the same shape. They are isosceles trapezoids with the upper base being half the length of the lower base and the upper base being equal to the length of the left and right sides. When viewed vertically with the convex portion 11 and the concave portion 12 overlapping vertically, they appear to form a regular hexagon.

[0037] The gas flow path P that allows exhaust gas G to pass through is formed by the aforementioned protrusions 11 or concave portions 12 and other metal plates 9 above and below, through the stacked metal plates 9. In other words, multiple metal plates 9 are stacked such that the protrusions 11 and concave portions 12 each form the gas flow path P, and the positions of the protrusions 11 and concave portions 12 are staggered. That is, in order to prevent the protrusions 11 and concave portions 12 in the upper and lower metal plates 9 from intersecting each other, the relative positions of the metal plates 9 are staggered. In the example described here, since the protrusions 11 and concave portions 12 are each formed into isosceles trapezoids that are equivalent to half of a regular hexagon, the metal plates 9 are stacked in a manner that forms a regular hexagon (or a regular hexagon missing one side) at the continuous positions of the protrusions 11 and concave portions 12 in the stacking direction of the metal plates 9.

[0038] An example of this stacked state is shown below Figure 6 . Figure 6 This is an end-face view showing the shape of the end face when two stacked metal plates 9 are cut along a transverse plane in this state. Therefore, in Figure 6 In this text, other protrusions 11 or recesses 12 arranged longitudinally are omitted. Figure 6 In the example shown, the convex portions 11 and the concave portions 12 are adjacent to each other in the horizontal direction and continuous vertically.

[0039] More specifically, the lower bottom edge of the upper protrusion 11 coincides with the upper bottom (top surface 11a) edge of the lower protrusion 11, thus the inclined surface of one waist of the trapezoid in the lower protrusion 11 and the continuous flat plate connecting portion 13 together with the upper protrusion 11 form a regular hexagon. Additionally, as... Figure 6 As shown by the dashed line, the regular hexagon is a shape with one side open.

[0040] Similarly, the bottom edge of the upper recess 12 coincides with the opening edge (through hole 16 side) of the lower recess 12, thus the inclined surface of one waist of the trapezoid in the upper recess 12 and the continuous flat plate connecting portion 13 together with the lower recess 12 form a regular hexagon. Furthermore, this regular hexagon is open on one side. The two flow paths of this open-side regular hexagon are connected by the flow path formed by the upper and lower connecting portions 13 between them to form a unit flow path. That is, it becomes a division section that can be called a unit flow channel. As described above, by setting the flow path length of this unit flow channel to "Le / 2" or less, the influence of diffusion resistance caused by the boundary film can be suppressed. In this case, the hydraulic diameter for determining the flow path length can be calculated simply by the cross-sectional area of ​​the flow path formed by the two open-side regular hexagons and the flow path formed by the upper and lower connecting portions 13 between them, and the length (perimeter) of the outline of the cross-sectional shape of this flow path, i.e., the "wetting perimeter".

[0041] As described above, the protrusion 11 and the recess 12 are connected vertically to form a gas flow path P with a predetermined opening shape (cross-sectional shape). Therefore, the top surface 11a (upper base in the trapezoid) of the protrusion 11 contacts the connecting portion 13 in the upper metal plate 9, and the two are joined at this point. Similarly, the bottom surface (lower base in the upside-down trapezoid) of the recess 12 contacts the connecting portion 13 in the lower metal plate 9, and the two are joined at this point. Therefore, not only is the area of ​​the stacked metal plates 9 joined together sufficiently wide, but the number of joining points is also large, thus enabling a firm connection between the metal plates 9, thereby increasing the strength of the catalyst unit 8 or the exhaust gas purification device 1 in the stacking direction.

[0042] As described above, the protrusions 11 and recesses 12 constituting the gas flow path P are alternately arranged in the longitudinal direction of the metal plate 9 and staggered in the transverse direction. Furthermore, the protrusions 11 and recesses 12 are stacked such that they are not aligned in a straight line in the longitudinal direction. Therefore, when the stacked metal plates 9 are cut in a transverse plane and viewed longitudinally, the shape of the cut end face is as described above. Figure 6As shown, other protrusions 11 and recesses 12 are arranged longitudinally from this end face, respectively forming gas flow paths P. Therefore, these other protrusions 11 and recesses 12 arranged longitudinally are visible as a cross-sectional shape. A portion of this cross-sectional shape is shown in... Figure 7 .exist Figure 7 In the diagram, the shaded portion represents the cut-off end face, while the unshaded portion represents the end faces of the protrusions 11 and concave portions 12 separated longitudinally from the cut-off end face. Therefore, the protrusions 11 or concave portions 12 of the stacked metal plates 9 partially overlap longitudinally. Consequently, these overlapping portions engage longitudinally, thus preventing the individual metal plates 9 from moving longitudinally. As a result, the strength of the metal plates 9 or the catalyst unit 8 increases longitudinally.

[0043] Furthermore, the flat connecting portion 13 functions to form or divide the gas flow path vertically and to connect the metal plates 9 to each other at predetermined intervals. Therefore, the exhaust purification device 1 or catalyst unit 8 is established with the same concave-convex shape of metal plates 9 as constituent components, thereby reducing the number or types of constituent components and making the construction or manufacturing / assembly easier.

[0044] Through the stacked metal plates 9, the aforementioned protrusions 11 and recesses 12 constitute gas flow paths P, through which the exhaust gas G introduced from the aforementioned inflow pipe 6 flows. Figure 3 An example of the flow pattern of exhaust gas G is indicated by an arrow. For example, gas flow path P is formed by an inclined surface (the waist in a trapezoid) or connecting portion 13 of an upper protrusion 11 and a lower recess 12 bounded by the aforementioned through hole 16. This gas flow path P is interrupted in its longitudinal length by the protrusion 11 or the recess 12, so the exhaust gas enters the next gas flow path. In this case, there is a flat plate-shaped connecting portion 13 at the outlet side of each gas flow path P, so the exhaust gas flows vertically and vertically. Furthermore, the protrusions 11 and recesses 12 arranged in the longitudinal direction are staggered in the transverse direction, so there is a longitudinal wall portion (equivalent to the waist in a trapezoid) of another gas flow path that is continuous with it at the outlet side of each gas flow path P, so the exhaust gas flows horizontally and vertically.

[0045] Thus, the exhaust gas enters and exits in a short gas flow path, and flows longitudinally while simultaneously separating, merging, and dispersing. During this process, the exhaust gas comes into contact with the catalyst 10 attached to the surfaces of the protrusions 11 and recesses 12, resulting in the oxidation or reduction of contaminants via the catalyst 10, thereby purifying the exhaust gas. Furthermore, as described above, the longitudinal length of each protrusion 11 and recess 12 is shortened to take into account the formation of a boundary film, thus reducing the boundary film diffusion resistance in each gas flow path P and enabling efficient purification of the exhaust gas based on the catalyst reaction.

[0046] Here, another embodiment of the present invention will be described. In this embodiment, the gas flow path P formed by the protrusion 11 or the recess 12 is not arranged in a straight line in the longitudinal direction of the exhaust flow, but is staggered from each other in the transverse direction, so that the gas flow path P is interrupted along the length of the protrusion 11 and the recess 12. This configuration can achieve the effect described above. Figure 6 Instead of stacking the metal plates 9 as shown, a different stacking method is used.

[0047] Figure 8 This refers to other stacking methods of metal plate 9 as described above. Figure 6 The same end view shows an example in which an inclined surface (the waist portion in the trapezoid) of a recess 12 in the upper metal plate 9 and an inclined surface (the waist portion in the trapezoid) of a protrusion 11 in the lower metal plate 9, parallel to it, are closely fitted together, and the top surface 11a of the protrusion 11 or the bottom surface 12a of the recess 12 is closely fitted together with the connecting portion 13 of the metal plate 9 on the other side, thus joining the metal plates 9 at least through their connecting portions 13. Figure 8 In the example shown, the metal plates 9 also form gas flow paths with each other, but especially as Figure 8 As shown by the dashed line, a gas flow path with a hexagonal cross-section is formed on the lower side of the protrusion 11 or the upper side of the concave portion 12.

[0048] Furthermore, the protrusion 11 and recess 12 in the embodiments of the present invention can be as follows: Figures 3 to 5 Instead of arranging them as shown, they are arranged in other patterns. Figure 9 One example is shown here, in which the protrusions 11 and recesses 12 are arranged in a straight line at a predetermined interval in the transverse direction. As an example, the distance between the protrusions 11 and recesses 12 in the transverse direction is the length of the protrusions 11 and recesses 12 in the transverse direction. In the longitudinal direction, the protrusions 11 and recesses 12 are adjacent, and the protrusions 11 and recesses 12 are arranged alternately. Furthermore, adjacent protrusions 11 and recesses 12 are offset by a half-distance in the transverse direction. With this configuration, by overlapping the metal plates 9 such that the upper protrusions 11 cover the lower recesses 12 and joining them with the connecting portion 13, a gas flow path P extending longitudinally is formed by these protrusions 11 and recesses 12. Furthermore, since these gas flow paths P are offset by a half-distance in the transverse direction, the exhaust gas flows vertically and transversely in a segmented manner each time it enters or exits the gas flow path. That is, the flow path is interrupted before the thickness of the boundary film reaches half the inner diameter of the gas flow path, which can suppress the increase of boundary film diffusion resistance.

[0049] As an example, the protrusion 11 and recess 12 in the metal plate 9 can be formed by stamping. In this case, the shapes of the protrusion 11 and recess 12 can be set to appropriate shapes corresponding to the shape of the mold. In the above embodiment, the opening shape (or cross-sectional shape) of the protrusion 11 and recess 12 is set to an isosceles trapezoid, but it can also be replaced by an isosceles triangle, rectangle, semicircular arc, semi-elliptical arc, etc. When it is set to an isosceles triangle, the opening shape of the gas flow path formed by the protrusion 11 and recess 12 becomes a rhombus. Furthermore, depending on the height of the triangle, it becomes a rhombus with pointed top and bottom or a rhombus that expands left and right. Furthermore, if it is rectangular, the opening shape of the gas flow path becomes a rectangle or a square. Moreover, if it is semicircular arc, the opening shape of the gas flow path becomes a circle, and if it is semi-elliptical arc, the opening shape of the gas flow path becomes an ellipse.

[0050] The opening shape of the gas flow path P formed by the protrusion 11 and the recess 12 is related to the pressure loss or contact of the flowing exhaust gas. Therefore, it is preferable to determine the shape of the protrusion 11 and the recess 12 considering the required pressure loss or contact. Here, "contact" refers to the number of times (frequency) that contaminants contained in the exhaust gas G come into contact with the inner surface of the gas flow path P or the catalyst 10 per unit time. The inventors of this invention have confirmed through research that the pressure loss decreases sequentially from rhombus to square to regular hexagon, and that the contact is good. Furthermore, regarding the rhombus shape, it has been confirmed that the closer the ratio of the diagonal lengths is to "1", the smaller the pressure loss and the better the contact.

[0051] Furthermore, the present invention is not limited to the above-described embodiments. The directions such as "longitudinal," "horizontal," and "up and down" in the above embodiments are directions for convenience based on the illustration of the figures. The arrangement direction of the metal plate 9, the catalyst unit 8, or the exhaust purification device 1 is not limited to the orientation described in the above embodiments. Also, in the above embodiments, the protrusions 11 and concave portions 12 are set to the same shape with reverse vertical rotation, but in the present invention, these can have different heights or shapes on the surface side and the back side. In this case, the metal plates can be stacked as long as the surfaces forming the protrusions face each other or the surfaces forming the concave portions face each other. Moreover, in the exhaust purification device of the present invention, sometimes exhaust flows between the flat plate-shaped connecting portions in the stacked upper and lower metal plates, so the portion between the connecting portions also becomes a gas flow path.

Claims

1. An exhaust gas purification device that purifies exhaust gas generated by combustion by circulating it along a metal plate that serves as a substrate carrying a catalyst, characterized in that... It has: a convex portion, which is a strip-shaped portion divided by the cut portions at the front and rear sections in the longitudinal direction of the exhaust flow of the metal plate, bent or flexed towards one side of the metal plate, i.e., the surface side, to form a protruding gas flow path; and a concave portion, which is another strip-shaped portion divided by the cut portions at the other front and rear sections in the longitudinal direction of the exhaust flow of the metal plate, bent or flexed towards the other side of the metal plate, i.e., the back side, to form a recessed gas flow path, and The portion divided by the cut-off part is called a through hole. The protrusions and the recesses are alternately formed side-by-side in at least one of the longitudinal direction and the transverse direction orthogonal to the longitudinal direction, separated by a predefined plate-shaped connecting portion. The catalyst is attached to a plurality of metal plates on the surface side and the back side, including the protrusions and the recesses, and the protrusions are stacked such that the protrusions are staggered from each other in the lateral direction and the recesses are staggered from each other. Furthermore, adjacent metal plates in the stacking direction are connected at least by the plate-shaped connecting portion.

2. The exhaust gas purification device according to claim 1, characterized in that, The top surface of the protrusion engages with the flat connecting portion of the other metal plates located on the upper side in the stacking direction, and The bottom surface of the recess engages with the flat connecting portion of the other metal plates located on the lower side in the stacking direction.

3. The exhaust gas purification device according to claim 1 or 2, characterized in that, In the metal plate, The protrusions and the recesses are arranged alternately side by side in the transverse direction, and They are arranged alternately in the longitudinal direction and staggered from each other in the transverse direction.

4. The exhaust gas purification device according to claim 1 or 2, characterized in that, In the metal plate, The protrusions are arranged in multiple rows in the transverse direction. The recesses are arranged in the transverse direction between the columns of the protrusions.

5. The exhaust gas purification device according to claim 1 or 2, characterized in that, The length of the connecting portion in the longitudinal direction is a predetermined length with an upper limit of length Le, determined by the following formula, and The length of the protrusion and the recess in the longitudinal direction is a predetermined length, with an upper limit of half of the length Le determined by the following formula. Le={dH / 9.28×√(ρ·u / μ)} 2 dH: hydraulic diameter (m), ρ: gas density (kg / m³) 3 u: gas velocity (m / s), μ: gas viscosity (Pas).

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