JP2014134122A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine, capable of suppressing unburned PM at an outer periphery of a DPF to suppress an increase in pressure loss and suppressing a power reduction or deterioration in fuel consumption.SOLUTION: An exhaust emission control device 1 includes: a filter 21 provided in an exhaust pipe 3 of an internal combustion engine 2 and for collecting PM in exhaust; and first and second catalysts provided upstream of the filter 21 and for purifying a gas composition in the exhaust. The first and second catalysts are carried by a honeycomb base 11, which has: a plurality of cells which extend from an end surface 11c on an inflow side of the exhaust to an end surface 11d on an outflow side thereof and serve as exhaust channels; and porous partition walls forming the cells in a partitioned manner. The cells on the center part 11a in the radial direction of the honeycomb base 11 penetrate from the end surface 11c on the inflow side to the end surface 11d on the outflow side. In the cells at an outer periphery 11b in the radial direction of the honeycomb base 11, a particulate matter collection part 15 is formed which collects the PM in the exhaust by closing the cells.

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine. More specifically, the present invention relates to an exhaust gas purification apparatus that includes a filter that collects particulate matter in exhaust gas and an exhaust gas purification catalyst that is provided upstream of the filter and purifies gas components in the exhaust gas.

  Conventionally, an exhaust gas purification apparatus for an internal combustion engine has been proposed in which a NOx catalyst or an oxidation catalyst is provided upstream of the exhaust passage of the internal combustion engine, and a DPF is provided downstream (see, for example, Patent Document 1). In this exhaust purification device, NOx, CO, and HC gas components in the exhaust are purified by the upstream NOx catalyst and oxidation catalyst, and particulate matter in the exhaust is collected by the downstream DPF.

  In the DPF, when the collected particulate matter gradually accumulates, a differential pressure is generated between the upstream side and the downstream side of the DPF, leading to a decrease in output and a deterioration in fuel consumption. For this reason, the DPF carries an oxidation catalyst for burning and removing the accumulated particulate matter and regenerating the DPF.

JP 2002-295244 A

  However, the outer peripheral portion of the DPF in the radial direction has poor gas contact, and particulate matter is likely to remain unburned even after regeneration. Therefore, as a result of the increase in pressure loss, there is a problem in that output is reduced and fuel consumption is deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to suppress an increase in pressure loss by suppressing unburned particulate matter in the outer peripheral portion of the DPF in the radial direction, thereby reducing output and reducing fuel consumption. An object of the present invention is to provide an exhaust emission control device for an internal combustion engine that can suppress the above.

  In order to achieve the above object, the present invention is provided in an exhaust passage (for example, an exhaust pipe 3 to be described later) of an internal combustion engine (for example, an internal combustion engine 2 to be described later) to collect particulate matter (PM) in the exhaust. Exhaust gas purification comprising a filter (for example, a filter 21 to be described later) and an exhaust purification catalyst (for example, a first catalyst and a second catalyst to be described later) provided upstream of the filter and purifying gas components in the exhaust gas. The exhaust purification catalyst is a device (for example, an exhaust purification device 1 described later), and the exhaust purification catalyst extends from an exhaust inflow end surface (for example, an inflow side end surface 11c described later) to an outflow side end surface (for example, an outflow side end surface 11d described later) Is supported by a honeycomb base material (for example, a honeycomb base material 11 described later) having a plurality of cells extending to the exhaust flow path and porous partition walls that define the cells. Radial center (example For example, a cell in the center portion 11a) described later penetrates from the end surface on the inflow side to the end surface on the outflow side, and the cell in the outer peripheral portion in the radial direction of the honeycomb substrate (for example, the outer periphery portion 11b described later) An exhaust gas purification apparatus characterized in that a particulate matter collection part (for example, a particulate matter collection part 15 described later) for closing particulate matter in exhaust gas by closing the cell is formed. provide.

  In the present invention, in the exhaust gas purification apparatus in which the honeycomb substrate carrying the exhaust gas purification catalyst is provided upstream of the filter, the cell in the radial center of the honeycomb substrate (hereinafter simply referred to as “center”). While the exhaust gas is allowed to penetrate from the inflow side end surface to the outflow side end surface, the cells in the radial outer peripheral portion (hereinafter, simply referred to as “peripheral portion”) of the honeycomb base material are closed and exhausted. A particulate matter collecting part for collecting the particulate matter is formed. Thereby, since the particulate matter can be collected at the outer peripheral portion of the upstream honeycomb substrate, the inflow amount of the particulate matter at the outer peripheral portion of the downstream DPF can be reduced. Therefore, the unburned residue of the particulate matter at the outer periphery of the DPF can be suppressed, and an increase in pressure loss can be suppressed. As a result, a decrease in output and a deterioration in fuel consumption can be suppressed.

  In this case, a first catalyst (for example, a first catalyst described later) for purifying a gas component in the exhaust is carried at the radial center of the honeycomb substrate, and the radial outer periphery of the honeycomb substrate is supported. It is preferable that a second catalyst (for example, a second catalyst described later) having a higher oxidizing ability with respect to the particulate matter than the first catalyst is supported.

In recent years, there has been a strong demand for reducing the use of precious metals, but with the reduction in size and fuel consumption of vehicles, the exhaust flow rate is lower and the exhaust temperature is lower than before. Therefore, there is a demand for early activation of these catalysts by suppressing the temperature decrease of the upstream NOx catalyst and oxidation catalyst.
Therefore, according to the present invention, the central part of the honeycomb base material carries the first catalyst for purifying the gas component in the exhaust gas, and the outer peripheral part has higher oxidizing ability for the particulate matter than the first catalyst. A second catalyst is supported. As a result, the particulate matter collected at the outer peripheral portion of the honeycomb base material is burned by the second catalyst, whereby the temperature reduction of the first catalyst in the central portion can be suppressed by the combustion heat, and early activation can be achieved. Therefore, since the purification efficiency of the first catalyst can be improved, the amount of noble metal can be reduced and the cost can be reduced.

  In this case, a case (for example, a case 30 to be described later) that accommodates the honeycomb substrate and a holding member (for example, a member that is provided between the honeycomb substrate and the case and holds the honeycomb substrate in the case) A first holding mat 41 described later, and the holding member is a main body (for example, a main body described later) wound around the outer peripheral surface (for example, outer peripheral surface 11e described later) of the honeycomb base material. 411) and an extension part (for example, extension parts 413 and 413 described later) extended from the main body part to the downstream side of the outflow side end face of the honeycomb substrate, and the particulate matter collection part Is preferably formed by bending the extension part until it contacts the outflow side end face of the outer peripheral part of the honeycomb base material to close the cells of the outer peripheral part of the honeycomb base material.

  In this invention, the particulate matter collection part on the outer peripheral part of the honeycomb substrate is formed by the holding member that is provided between the honeycomb substrate and the case and holds the honeycomb substrate in the case. More specifically, an extension portion extending from the main body wound around the outer peripheral surface of the honeycomb base material to the downstream side of the outflow side end surface of the honeycomb base material is brought into contact with the outflow side end surface of the outer peripheral portion of the honeycomb base material. The particulate matter collecting part is formed by closing the cells on the outer peripheral part of the honeycomb base material by bending to the end. As a result, the above-described effects can be reliably obtained, and the manufacturing cost can be reduced as compared with the case where the particulate matter collecting part is formed by plugging the cells in the outer peripheral part of the honeycomb base material with a plugging agent, for example. it can.

  In this case, it is preferable that the extension portion is not provided on a part of the entire circumference of the main body portion.

In each of the above-described inventions, when an extension is provided over the entire circumference of the main body wound around the outer peripheral surface of the honeycomb substrate, when the extension is bent, the holding members interfere with each other at the bent portion. As a result, the surface pressure received by the honeycomb base material 11 cannot be made uniform and the surface pressure is locally increased. As a result, the honeycomb base material may be damaged.
Therefore, in the present invention, the extension portion is not provided over the entire circumference of the main body portion, and the extension portion is not provided in a part thereof. Accordingly, the holding member can be prevented from being crushed when the extension portion is bent, and the honeycomb base material can be prevented from being damaged.

  In this case, it is preferable that the filter is accommodated in the single case together with the honeycomb substrate, and the honeycomb substrate and the filter are arranged on the same axis (for example, an axis X described later). .

In each of the above-described inventions, when the honeycomb substrate and the filter are arranged far away from each other, the particulate matter in the exhaust gas diffuses before flowing into the filter, so the particulate matter on the outer periphery of the filter There is a risk that the inflow of water cannot be reduced sufficiently. Therefore, in the present invention, the honeycomb substrate and the filter are accommodated in a single case. Thereby, since the honeycomb substrate and the filter can be arranged close to each other, the above-described effects of the invention can be obtained more reliably.
In each of the above-described inventions, when the axial direction of the honeycomb substrate and the axial direction of the filter do not match, for example, when the exhaust passage between the honeycomb substrate and the filter is bent, There is a possibility that the inflow amount of the particulate matter to the outer peripheral portion cannot be sufficiently reduced. Therefore, in the present invention, the honeycomb base material and the filter are arranged on the same axis. Thereby, the effect of the above-mentioned invention is acquired more reliably.

  In this case, the case has a small-diameter portion (for example, a small-diameter portion 34 described later) whose inner diameter is smaller than the diameter of the honeycomb base material, and the honeycomb base material is between the outflow side end surface and the small-diameter portion. It is preferable that the extension is held in the state.

  In the present invention, a small diameter portion having an inner diameter smaller than the diameter of the honeycomb base material is formed in the case, and an extension portion is interposed between the outflow side end face and the small diameter portion to hold the honeycomb base material. Thereby, the above-described effects can be obtained, and positioning of the honeycomb base material in the case is facilitated.

  ADVANTAGE OF THE INVENTION According to this invention, the exhaust gas purification apparatus of the internal combustion engine which can suppress the unburned residue of the particulate matter in the outer peripheral part of DPF, can suppress the increase in pressure loss, and can suppress the fall of output and a deterioration of a fuel consumption by extension can be provided.

1 is a perspective view showing an exhaust emission control device for an internal combustion engine according to an embodiment of the present invention. It is an axial sectional view of the exhaust emission control device according to the embodiment. It is a figure for demonstrating the honeycomb base material and 1st holding mat which concern on the said embodiment, (a) is a figure which shows the state before winding a 1st holding mat around the outer peripheral surface of a honeycomb base material. (B) is a figure which shows the state by which the 1st holding mat was wound by the outer peripheral surface of the honeycomb base material. It is a figure which shows the modification of a 1st holding mat. It is a figure for demonstrating the loading method of the 1st catalyst which concerns on the said embodiment, and a 2nd catalyst, (a) is a figure which shows the loading method of a 1st catalyst, (b) is a figure of a 2nd catalyst. It is a figure which shows the carrying | support method. It is a diagram for explaining a method for forming a particulate matter collection portion according to the embodiment, wherein (a) accommodates in a case a honeycomb base material in which a first holding mat is wound around an outer peripheral surface, It is a figure which shows a state when pushing in the downstream small diameter part side, (b) is a figure which shows the state after pushing in.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an exhaust purification device 1 for an internal combustion engine 2 according to an embodiment of the present invention. The internal combustion engine 2 is a diesel engine, and the exhaust purification device 1 purifies gas components (NOx, CO, and HC) in the exhaust and purifies particulate matter (hereinafter referred to as “PM”) in the exhaust. . As shown in FIG. 1, the exhaust purification device 1 is provided in an exhaust pipe 3 that extends downward along the side surface of the internal combustion engine 2. That is, the exhaust purification device 1 is provided in the exhaust pipe 3 with the exhaust flow direction directed downward.

  As shown in FIG. 1, the exhaust purification device 1 includes an exhaust purification catalyst unit 10 and a DPF 20 that are arranged in order from the upstream side. Here, FIG. 2 is an axial sectional view of the exhaust emission control device 1. As shown in FIG. 2, the exhaust purification catalyst unit 10 disposed on the upstream side and the DPF 20 disposed on the downstream side are accommodated in a single case 30. That is, the exhaust purification catalyst unit 10 and the DPF 20 are disposed close to each other. Further, the exhaust purification catalyst unit 10 and the DPF 20 are disposed on the same axis X.

The exhaust purification catalyst unit 10 includes a honeycomb substrate 11, a first catalyst, a second catalyst, and a first holding mat 41.
The honeycomb substrate 11 is formed in a columnar shape having a smaller diameter than that of a filter 21 described later and having a substantially circular cross section. The honeycomb substrate 11 is a flow-through type honeycomb having a plurality of cells extending from the exhaust inflow end surface 11c to the outflow side end surface 11d and serving as exhaust passages, and porous partition walls defining the cells. It is a substrate.

  Examples of the material of the honeycomb substrate 11 include cordierite, alumina titanate, and mullite. As will be described later, in the present embodiment, from the viewpoint of positioning and holding the honeycomb substrate 11 using the small-diameter portion 34 of the case 30, soft cordierite is preferably used among the above materials.

  Each cell of the central portion 11a in the radial direction of the honeycomb substrate 11 is open without being sealed, and penetrates from the exhaust inflow end surface 11c to the outflow side end surface 11d. On the other hand, in each cell of the outer peripheral portion 11b in the radial direction of the honeycomb base material 11, a particulate matter collecting portion 15 that closes the cell and collects PM in the exhaust is formed. The particulate matter collecting unit 15 will be described in detail later.

  The first catalyst is supported on the radial center portion 11 a of the honeycomb substrate 11. The first catalyst is a NOx catalyst such as an oxidation catalyst or a NOx storage catalyst (LNC). Specifically, for example, the first catalyst includes at least one noble metal of Pt, Pd, and Rh, zeolite, Ba, and Ce. The first catalyst may be carried on the outer peripheral portion 11b.

  The second catalyst is supported on the outer peripheral portion 11 b in the radial direction of the honeycomb substrate 11. The second catalyst is a PM combustion catalyst having a higher oxidizing ability for PM than the above-mentioned first catalyst. Specifically, for example, the second catalyst includes Ag and at least one noble metal of Pt and Pd. This Ag-based PM combustion catalyst has the most excellent PM oxidation ability, and can oxidize and purify PM from a lower temperature than other PM combustion catalysts.

  The first holding mat 41 is a holding member that is provided between the honeycomb substrate 11 and the case 30 and holds the honeycomb substrate 11 in the case 30. The first holding mat 41 is wound around the outer peripheral surface 11e of the honeycomb base material 11 so as to cover the outer peripheral surface 11e of the honeycomb base material 11 over the entire periphery. However, the first holding mat 41 is not provided on a part of the outer peripheral surface 11e of the honeycomb substrate 11 on the upstream side.

  As the first holding mat 41, a material having heat resistance, vibration resistance and sealing properties is used. Specifically, ceramic fibers such as alumina fibers, silica fibers, alumina silica fibers, and ceramic glass fibers are used.

  Here, FIG. 3 is a diagram for explaining the honeycomb base material 11 and the first holding mat 41. FIG. 3A shows a state before winding the first holding mat 41 around the outer peripheral surface 11e of the honeycomb base material 11. (B) is a diagram showing a state in which the first holding mat 41 is wound around the outer peripheral surface 11e of the honeycomb base material 11. FIG. As shown in FIG. 3A, the first holding mat 41 is a sheet-like holding member, and includes a main body part 411, a matching part 412, and extension parts 413 and 413.

The main body portion 411 has a substantially rectangular shape mainly constituting the first holding mat 41 and is a portion wound around the outer peripheral surface 11 e of the honeycomb substrate 11.
The alignment portion 412 includes a convex portion 412a provided at one end (the right end in FIG. 3) in the winding direction of the main body 411 (the longitudinal direction of the main body in FIG. 3A) and the other end. And a concave portion 412b provided in the portion (the left end portion in FIG. 3A). As shown in FIG. 3B, the convex portions 412a and the concave portions 412b wind the first holding mat 41 around the outer peripheral surface 11e of the honeycomb base material 11, and abut both end portions of the main body portion 411 in the winding direction. Sometimes they can be fitted together.

  The extension portions 413 and 413 are spaced outward from one end in the direction orthogonal to the winding direction of the main body 411 (the lower end in FIG. 3A) with a predetermined interval in the winding direction. Each is an extended part. The first holding mat 41 is wound around the outer peripheral surface 11e of the honeycomb substrate 11 so that the extended portions 413 and 413 extend downstream from the outflow side end surface 11d of the honeycomb substrate 11. That is, these extended portions 413 and 413 are portions that extend downstream from the outflow side end surface 11d of the honeycomb base material 11 when the first holding mat 41 is wound around the outer peripheral surface 11e of the honeycomb base material 11. It is.

  In the present embodiment, the extension portions 413 and 413 are opposite to each other via the axis X when the first holding mat 41 is wound around the outer peripheral surface 11e of the honeycomb substrate 11, and the case half 30a described later. , 30b are provided so as to be arranged at positions corresponding to the tops. Further, at this time, the extension portions 413 and 413 are not provided on a part of the entire circumference of the main body portion 411 wound around the outer peripheral surface 11e of the honeycomb substrate 11, and the extension portions 413 and 413 are provided. The part which is not made is arrange | positioned in the position corresponding to the butting | matching part 33 of case half 30a, 30b. Thereby, the biting of the first holding mat 41 (extension portions 413 and 413) in the butting portion 33 is avoided.

Here, FIG. 4 is a view showing a first holding mat 41A which is a modification of the first holding mat 41. As shown in FIG. As shown in FIG. 4, the first holding mat 41 </ b> A has the same configuration as the first holding mat 41 described above except that the extension portion has a different configuration.
The extension portions 413A and 413A of the first holding mat 41A are longer in the winding direction of the main body portion 411 than the extension portions 413 and 413 described above. That is, in this modification, except for the notch portion 414 shown in FIG. 4 formed between the extension portions 413A and 413A, one end portion in the direction orthogonal to the winding direction of the main body portion 411 (in FIG. The extension portions 413A and 413A are extended outward from the end portion on the side. Thereby, when the extension part is bent as described later, the honeycomb base material 11 is prevented from being damaged due to the collapse due to the interference between the first holding mats 41A (extension parts 413A and 413A). Almost all the cells of the outer peripheral portion 11b can be closed, and the particulate matter collecting portion 15 can be formed over a wider range.

Returning to FIG. 2, the particulate matter collection part 15 is formed in the cell of the outer peripheral part 11 b of the honeycomb substrate 11. PM in the exhaust gas flowing into the cells of the outer peripheral portion 11b of the honeycomb base material 11 is collected by the particulate matter collecting portion 15.
More specifically, the particulate matter collection unit 15 bends the above-described extensions 413 and 413 until it contacts the outflow side end surface 11d of the outer peripheral portion 11b of the honeycomb base material 11, and It is formed by closing the cell. That is, the particulate matter collecting unit 15 causes the extended portions 413 and 413 of the first holding mat 41 to wrap around the outflow side end surface 11d side of the honeycomb substrate 11, and the extended portions 413 and 413 wrap around It is formed by closing the cell.

  In addition, it is preferable that the formation range of the particulate matter collection part 15, ie, the number of cells to be blocked, is 10 cells or less. In the honeycomb base material 11, exhaust gas flows intensively into the cells of the central portion 11 a that penetrates from the inflow side end surface 11 c to the outflow side end surface 11 d, so that an increase in pressure loss can be ignored within the above range. Therefore, it is preferable to set the areas of the extended portions 413 and 413 of the first holding mat 41 that wrap around the outflow side end face 11d side of the honeycomb base material 11 so that the number of cells to be closed is within the above range.

As shown in FIG. 2, the DPF 20 includes a filter 21, a PM combustion catalyst, and a second holding mat 42.
The filter 21 is formed in a cylindrical shape having a larger diameter than the above-described honeycomb substrate 11 and a substantially circular cross section. Heretofore, it has been found that when the downstream filter has a larger diameter than the upstream honeycomb substrate, unburned PM is likely to occur at the radially outer periphery of the filter. In this respect, in this embodiment, since PM is collected by the particulate matter collection unit 15 formed on the outer peripheral part 11b of the upstream honeycomb base material 11 as described above, the PM is collected on the outer peripheral part 21b of the filter 21. As a result of the reduction in the amount of inflowing PM, unburned PM is suppressed. That is, by making the filter 21 larger in diameter than the honeycomb substrate 11, the effect of the present embodiment is greatly exerted.

  The filter 21 includes a plurality of cells that extend from the exhaust inflow end surface 21c to the outflow end surface 21d and serve as exhaust flow paths, and porous partition walls that define the cells. Each of the plurality of cells constituting the filter 21 has a plugged portion in which at least one of the openings on the inflow side end surface and the outflow side end surface is sealed with a plugging agent. Sealing portions are alternately provided in a checkered pattern for each adjacent cell on each of the exhaust inflow side end surface and the outflow side end surface. That is, the filter 21 is a sealed wall flow type filter, and PM in exhaust gas that has flowed in is collected by the filter 21.

  The filter 21 is formed with an annular convex portion 211 that protrudes outward, that is, toward the case 30 over the entire circumference at a substantially central portion of the outer peripheral surface 21e in the axis X direction. The annular convex portion 211 is formed integrally with the filter 21. The annular convex portion 211 can be fitted into an annular concave portion 35 formed in the case 30 to be described later, and when the annular convex portion 211 and the annular concave portion 35 are fitted via the second holding mat 42, The filter 21 is positioned and held in the case 30.

  Examples of the material of the filter 21 include silicon carbide (SiC), cordierite, alumina titanate, and mullite. As described above, in the present embodiment, from the viewpoint of integrally forming the annular convex portion 211 on the outer peripheral surface 21e of the filter 21, among the above materials, hard SiC that is easy to form the annular convex portion 211 on the outer peripheral surface 21e. Is preferably used.

The PM combustion catalyst is supported substantially uniformly on the entire filter 21. Thereby, PM collected by the filter 21 can be burned and removed.
In the present embodiment, the PM combustion catalyst carried on the filter 21 is the same as the second catalyst carried on the outer peripheral portion 11b of the honeycomb substrate 11 described above.

The second holding mat 42 is a holding member that is provided between the filter 21 and the case 30 and holds the filter 21 in the case 30. The second holding mat 42 has a substantially rectangular shape, is wound around the central portion of the outer peripheral surface 21e of the filter 21 in the axis X direction, and is provided so as to cover the outer peripheral surface 21e of the filter 21 over the entire circumference. Yes. That is, the second holding mat 42 is provided so as to cover the entire circumference of the annular convex portion 211 integrally formed on the outer peripheral surface of the filter 21.
In addition, as a material of the 2nd holding mat 42, the same thing as the 1st holding mat 41 mentioned above is used.

  The case 30 accommodates the honeycomb substrate 11 and the filter 21 as described above. The case 30 is a clamshell type case composed of case halves 30a and 30b that are divided into two on the circumference along the axis X direction. The case 30 is formed by welding the two half cases 30a and 30b at a butting portion 33 described later (see FIG. 1).

As shown in FIGS. 1 and 2, the case 30 includes a first housing portion 31, a second housing portion 32, a butting portion 33, a small diameter portion 34, and an annular recess 35.
The 1st accommodating part 31 accommodates the honeycomb base material 11 by which the 1st holding mat 41 was wound by the outer peripheral surface 11e in the upstream. The diameter of the 1st accommodating part 31 is smaller than the diameter of the 2nd accommodating part 32 mentioned later, and it is the diameter which can hold | maintain the honeycomb base material 11 in the state which compressed the 1st holding mat 41 between the honeycomb base materials 11. It is formed.

  The 2nd accommodating part 32 accommodates the filter 21 by which the 2nd holding mat 42 was wound by the outer peripheral surface 21e in the downstream. The diameter of the second housing portion 32 is larger than the diameter of the first housing portion 31 described above, and is formed to have a diameter capable of holding the filter 21 in a state where the second holding mat 42 is compressed between the second housing portion 32 and the filter 21.

  The butting portion 33 is a portion where the end portions of the case halves 30a and 30b are butted together. More specifically, the abutting portion 33 is formed in a flange shape with the radial end edges of the case halves 30a and 30b facing outward (see FIG. 1).

  The small diameter portion 34 is provided between the first storage portion 31 and the second storage portion 32 described above, and is formed with a smaller diameter than the first storage portion 31. As shown in FIG. 2, the small diameter portion 34 is formed such that the inclination angle on the first housing portion 31 side is relatively large. Therefore, the outflow side end surface 11 d of the outer peripheral portion 11 b of the honeycomb substrate 11 is supported via the first holding mat 41 by the inner wall inclined surface 34 c facing the upstream side of the small diameter portion 34. Thereby, the honeycomb substrate 11 is positioned and held in the case 30.

  The annular recess 35 is formed in a substantially central portion in the axial direction X of the second housing portion 32 by a recess that is recessed outward over the entire circumference. As described above, the annular recess 35 is formed so as to be fitted to the annular protrusion 211 formed on the outer peripheral surface 21 e of the filter 21 via the second holding mat 42.

Next, a method for manufacturing the exhaust emission control device 1 according to the present embodiment will be described with reference to FIGS.
Here, FIG. 5 is a diagram for explaining the loading method of the first catalyst and the second catalyst according to the present embodiment, and (a) is a diagram illustrating the loading method of the first catalyst, and (b) ) Is a diagram showing a method of supporting the second catalyst. FIG. 6 is a diagram for explaining a method of forming the particulate matter collecting unit 15 according to the present embodiment. FIG. 6A is a honeycomb diagram in which the first holding mat 41 is wound around the outer peripheral surface 11e. It is a figure which shows the state when the base material 11 is accommodated in the case 30, and is pushed in to the downstream small diameter part 34 side, (b) is a figure which shows the state after pushing.

First, the honeycomb base material 11 is manufactured in which the first catalyst is supported on the central portion 11a in the radial direction and the second catalyst is supported on the outer peripheral portion 11b.
Specifically, as shown in FIG. 5 (a), a masking member 310 having an opening corresponding to the center portion 11a is placed on one end face of the honeycomb substrate 11, and the first catalyst is placed there. Slurry 100 is poured. Thereafter, the first catalyst is supported on the central portion 11a of the honeycomb substrate 11 by drying.
Next, as shown in FIG. 5 (b), a masking member 320 a for concealing the central portion 11 a and an opening having a diameter equivalent to the diameter of the honeycomb base material 11 on one end face of the honeycomb base material 11. 320b is placed concentrically. The slurry 200 of the second catalyst is poured therein. Thereafter, the second catalyst is supported on the outer peripheral portion 11b of the honeycomb substrate by drying.
As described above, the honeycomb base material 11 in which the first catalyst is supported on the central portion 11a and the second catalyst is supported on the outer peripheral portion 11b is obtained.

  Next, as shown in FIG. 3B, the honeycomb base material 11 in which the first holding mat 41 is wound around the outer peripheral surface 11e is manufactured. Further, as described above, the filter 21 in which the second holding mat 42 is wound around the outer peripheral surface 21e is produced.

Next, as shown in FIG. 6 (a), the first holding mat 41 is placed in the outer peripheral surface 11e in the first housing portion 31a of one case half 30a placed substantially horizontally with the opening side facing upward. The honeycomb substrate 11 wound around is placed. At this time, the honeycomb substrate 11 is placed at a position shifted from the predetermined position to the upstream side (left side in FIG. 6A). Further, the honeycomb is so arranged that the lower extension portion 413 is disposed at a position corresponding to the top portion of the case half 30a and a portion where the extension portion 413 is not provided is disposed at a position corresponding to the abutting portion 33. The base material 11 is placed.
Further, the filter 21 in which the second holding mat 42 is wound around the outer peripheral surface 21e is placed in the second housing portion 32a. At this time, the filter 21 is placed at a position where the annular convex portion 211 is fitted into the annular concave portion 35 a of the case half 30 a via the second holding mat 42.

  In this state, as shown in FIG. 6A, the honeycomb base material 11 is pushed into the small diameter portion 34a side (the right side of FIG. 6A) by the push rod 400. Then, the outflow side end surface 11d of the outer peripheral portion 11b of the honeycomb base material 11 contacts the inner wall inclined surface 34c of the small diameter portion 34a through the extension portion 413 on the lower side of the first holding mat 41. At this time, since the inclination angle of the inner wall inclined surface 34c of the small diameter portion 34a is relatively large, the lower extended portion 413 of the first holding mat 41 is bent toward the outflow side end surface 11d. As a result, the bent lower extension portion 413 contacts the outflow side end surface 11d of the outer peripheral portion 11b of the honeycomb substrate 11, and closes the cells of the outer peripheral portion 11b.

Next, as shown in FIG. 6B, the other case half 30b is covered from above so that the annular recess 35b fits into the annular protrusion 211, and is brought into contact with and joined to the case half 30a. At this time, the upper extension 413 of the first holding mat 41 is bent toward the outflow side end face 11d. As a result, the bent upper extension portion 413 contacts the outflow side end surface 11d of the outer peripheral portion 11b of the honeycomb substrate 11, and closes the cells of the outer peripheral portion 11b.
As described above, the particulate matter collection unit 15 of the present embodiment is formed.

  Finally, after welding the butting portion 33 of the case 30, the exhaust purification device 1 according to the present embodiment is manufactured by attaching it to a predetermined position of the exhaust pipe 3.

According to this embodiment, the following effects are produced.
In the present embodiment, in the exhaust purification device 1 in which the honeycomb substrate 11 carrying the first catalyst and the second catalyst is provided upstream of the filter 21, the cells in the central portion 11a in the radial direction of the honeycomb substrate 11 are While passing from the exhaust inflow end surface 11c to the outflow end surface 11d, the cells on the outer peripheral portion 11b of the honeycomb substrate 11 close the cells and collect PM in the exhaust. 15 was formed. Thereby, since PM can be collected by the outer peripheral part 11b of the upstream honeycomb base material 11, the inflow amount of PM in the outer peripheral part 21b of the downstream filter 21 can be reduced. Therefore, unburned PM can be suppressed in the outer peripheral portion 21b of the filter 21, and an increase in pressure loss can be suppressed. As a result, a decrease in output and a deterioration in fuel consumption can be suppressed.

By the way, in recent years, there has been a strong demand for reducing the use of precious metals. On the other hand, with the reduction in size and fuel consumption of vehicles, the exhaust flow rate is lower and the exhaust temperature is lower than before. Therefore, there is a demand for early activation of these catalysts by suppressing the temperature decrease of the upstream NOx catalyst and oxidation catalyst.
Therefore, according to the present embodiment, the central part 11a of the honeycomb base material 11 carries the first catalyst for purifying the gas component in the exhaust gas, and the outer peripheral part 11b has the ability to oxidize PM rather than the first catalyst. A second catalyst having a high value was supported. Thereby, by burning PM collected by the outer peripheral part 11b of the honeycomb base material 11 with the second catalyst, the temperature reduction of the first catalyst in the central part 11a can be suppressed by the combustion heat, and early activation can be achieved. Therefore, since the purification efficiency of the first catalyst can be improved, the amount of noble metal can be reduced and the cost can be reduced.

  In the present embodiment, the particulate matter on the outer peripheral portion 11 b of the honeycomb substrate 11 is provided between the honeycomb substrate 11 and the case 30, and the first holding mat 41 that holds the honeycomb substrate 11 in the case 30. The collection part 15 is formed. More specifically, extension portions 413 and 413 extending from the main body portion 411 wound around the outer peripheral surface 11e of the honeycomb base material 11 to the downstream side of the outflow side end surface 11d of the honeycomb base material 11 are provided. The particulate matter collecting part 15 was formed by closing the cells of the outer peripheral part 11b of the honeycomb base material 11 by bending until it contacted the outflow side end face 11d of the outer peripheral part 11b. As a result, the above-described effects can be obtained with certainty, and the manufacturing cost can be compared to the case where the particulate matter collecting part is formed by plugging the cells of the outer peripheral part 11b of the honeycomb substrate 11 with a plugging agent, for example. Can be reduced.

When an extension is provided over the entire circumference of the main body 411 wound around the outer peripheral surface 11e of the honeycomb substrate 11, when the extension is bent, the first holding mats interfere with each other at the bent portion. As a result, the surface pressure received by the honeycomb base material 11 cannot be made uniform and the surface pressure is locally increased. As a result, the honeycomb base material 11 may be damaged.
Therefore, in this embodiment, the extension portions 413 and 413 are not provided over the entire circumference of the main body portion 411, but the extension portions 413 and 413 are not provided in a part thereof. Thereby, crushing of the 1st holding mat 41 when extending the extension parts 413 and 413 can be suppressed, and damage to the honeycomb substrate 11 can be suppressed.

  When the honeycomb substrate 11 and the filter 21 are arranged far away from each other, PM in the exhaust gas diffuses before flowing into the filter 21, so that a sufficient amount of PM flows into the outer peripheral portion 21 b of the filter 21. There is a risk that it cannot be reduced. Therefore, in the present embodiment, the honeycomb base material 11 and the filter 21 are accommodated in a single case 30. Thereby, since the honeycomb substrate 11 and the filter 21 can be arranged close to each other, the above-described effect can be obtained more reliably.

  Further, when the axial direction of the honeycomb base material 11 and the axial direction of the filter 21 do not coincide, for example, when the exhaust pipe between the honeycomb base material 11 and the filter 21 is bent, the outer periphery of the filter 21 There is a possibility that the amount of PM flowing into the portion 21b cannot be sufficiently reduced. Therefore, in this embodiment, the honeycomb base material 11 and the filter 21 are arranged on the same axis X. Thereby, the above-mentioned effect can be obtained more reliably.

  In the present embodiment, the small diameter portion 34 having an inner diameter smaller than the diameter of the honeycomb base material 11 is formed in the case 30, and the extended portions 413 and 413 are interposed between the outflow side end surface 11 d and the small diameter portion 34. The substrate 11 was held. Thereby, the above-described effects can be obtained, and the positioning of the honeycomb base material 11 in the case 30 is facilitated.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

  In the above embodiment, the particulate matter collecting part 15 is bent until it contacts the outflow side end face 11d of the outer peripheral part 11b of the honeycomb base material 11, thereby closing the cells of the outer peripheral part 11b of the honeycomb base material 11. However, it is not limited to this. For example, the particulate matter collection part 15 may be formed by sealing the outflow side end face of the cell of the outer peripheral part 11b with a sealant.

  In the above-described embodiment, the honeycomb base material 11 is positioned and held using the small diameter portion 34, but is not limited thereto. For example, the ring may be held by a ring member fitted to the outer periphery of the honeycomb substrate 11 and held. The same applies to the filter 21.

  In the above embodiment, the honeycomb base material 11 and the filter 21 have a circular column shape in cross section, but are not limited thereto. For example, it may be a columnar body having an elliptical or square cross section.

  In the above embodiment, the first catalyst is an oxidation catalyst or a NOx catalyst, and the second catalyst is a PM combustion catalyst. However, the present invention is not limited to this. As a result, the second catalyst only needs to have a higher PM oxidation capacity than the first catalyst. For example, the first catalyst and the second catalyst may be formed by mixing a plurality of catalysts.

  In the above embodiment, the clamshell method is adopted as the canning method, but the invention is not limited to this. For example, a press-fitting method may be adopted.

DESCRIPTION OF SYMBOLS 1 ... Exhaust purification device 2 ... Internal combustion engine 3 ... Exhaust pipe (exhaust passage)
DESCRIPTION OF SYMBOLS 11 ... Honeycomb base material 11a ... Center part 11b ... Outer peripheral part 11c ... Inflow side end surface 11d ... Outflow side end surface 11e ... Outer peripheral surface 15 ... Particulate matter collection part 30 ... Case 34 ... Small diameter part 41 ... 1st holding mat (holding) Element)
411 ... Main body 413 ... Extension X ... Axis

Claims (6)

A filter provided in an exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust;
An exhaust purification device comprising an exhaust purification catalyst provided upstream of the filter and purifying gas components in the exhaust,
The exhaust purification catalyst is carried on a honeycomb substrate having a plurality of cells that extend from an exhaust inflow side end surface to an outflow side end surface to serve as exhaust passages, and porous partition walls that define the cells,
The cell in the central portion of the honeycomb substrate in the radial direction penetrates from the inflow side end surface to the outflow side end surface,
An exhaust gas purification apparatus characterized in that a particulate matter collecting part for closing particulate matter in the exhaust gas and collecting particulate matter in the exhaust gas is formed in a cell in a radially outer peripheral portion of the honeycomb substrate. . A first catalyst for purifying a gas component in the exhaust is supported at the radial center of the honeycomb substrate.
2. The exhaust emission control device according to claim 1, wherein a second catalyst having a higher oxidizing ability with respect to particulate matter than the first catalyst is supported on an outer peripheral portion in a radial direction of the honeycomb base material. A case for accommodating the honeycomb substrate;
A holding member provided between the honeycomb base material and the case, and holding the honeycomb base material in the case;
The holding member has a main body wound around the outer peripheral surface of the honeycomb base, and an extension extending from the main body to the downstream side of the outflow side end surface of the honeycomb base,
The particulate matter collection part is formed by bending the extension part until it contacts the outflow side end surface of the outer peripheral part of the honeycomb base material to close the cells on the outer peripheral part of the honeycomb base material. The exhaust emission control device according to claim 1 or 2, characterized in that   The exhaust purification device according to claim 3, wherein the extension portion is not provided on a part of the entire circumference of the main body portion. The filter is housed in the single case together with the honeycomb substrate,
The exhaust emission control device according to claim 3 or 4, wherein the honeycomb substrate and the filter are arranged on the same axis. The case has a small diameter portion whose inner diameter is smaller than the diameter of the honeycomb substrate,
The exhaust emission control device according to any one of claims 3 to 5, wherein the honeycomb base material is held in a state where the extension portion is interposed between the outflow side end face and the small diameter portion.

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