JP2017053283A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact size, less pressure loss type exhaust emission control device of internal combustion engine showing a superior emission performance.SOLUTION: This invention relates to exhaust emission control device of internal combustion engine comprising a first exhaust emission control part 10 arranged at an exhaust passage 2 and carrying catalyst for controlling emission at a first honeycomb carrier 11; a second exhaust emission control part 20 arranged outside the first exhaust emission control part 10 and carrying catalyst for controlling emission at a second honeycomb carrier 21; and an exhaust emission flowing direction reversing part 40 for reversing a direction of the exhaust emission flowed out of the first exhaust emission control part 10 to guide it to the second exhaust emission control part 20. The first honeycomb carrier 11 has a helical cell structure where a plurality of first stage cells extend to draw a helical line from the exhaust flowing-in side toward its flowing-out side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust purification device provided in an exhaust passage of an internal combustion engine.

  Conventionally, various proposals have been made for downsizing an exhaust purification device provided in an exhaust passage of an internal combustion engine. For example, there has been proposed an exhaust emission control device in which exhaust gas flowing in from an inlet passes through a forward flow region of a honeycomb carrier, and is then redirected by a reversing unit and backflowed through a reflux region (for example, Patent Documents). 1). The exhaust purification device of Patent Document 1 requires only a small amount of built-in space, and in particular, the space on the side of the exhaust turbocharger can be effectively used.

  By the way, when it is configured to change the direction of the exhaust gas flow by the reversing means as in the exhaust gas purification device of Patent Document 1, the exhaust gas flow is biased. For this reason, in the area | region where the reverse exhaust gas flows, there exists a possibility that the volumetric efficiency of a catalyst may fall and purification performance may deteriorate. Moreover, there is a risk that the pressure loss related to the flow of exhaust gas will increase and the output of the internal combustion engine will decrease.

  In this situation, several techniques have already been proposed for dealing with the above-described problems when adopting a structure that reverses the flow of exhaust. In a part where the flow of the exhaust gas is reversed, a proposal to retreat the honeycomb carrier inlet at the reflux side start end with respect to the honeycomb carrier outlet at the rear end on the forward side (see, for example, Patent Document 2) or in the vicinity of the rear end on the forward side A proposal to provide a member for leading a part of the exhaust to the outer peripheral side (for example, see Patent Document 3).

  In addition, the above is a proposal regarding the structure of the catalytic converter which is an exhaust purification device, but there is also the following proposal regarding the honeycomb filter. That is, the cells from the exhaust inflow surface to the outflow surface of the honeycomb filter are formed in a spiral shape, and the soot and ash in the exhaust gas are effectively collected while following the spiral flow path of the cell. (For example, refer to Patent Document 4).

JP-T-2006-515401 Special table 2007-506893 Special table 2014-511969 gazette JP 2013-194469 A

As described above, the exhaust gas purification apparatus of Patent Document 1 has a problem in that the flow of exhaust gas is biased and the purification performance deteriorates or the pressure loss increases.
Further, in the exhaust gas purification device of Patent Literature 2, in order to cope with the above-described problem in the technology of Patent Literature 1, the dead space is larger than that of Patent Literature 1. For this reason, it is disadvantageous in terms of miniaturization.
Furthermore, in the exhaust gas purification apparatus of Patent Document 3, it is necessary to specially provide a member for leading a part of the exhaust gas to the outer peripheral side, and problems such as an increase in pressure loss arise.
On the other hand, the technique described in Patent Document 4 is applied to a filter (wall flow type) in which the flow path of the cell is blocked, and cannot be applied to a normal catalyst (wall through type). If it is to be applied, useless cells in which no exhaust flows will increase. That is, the dead volume increases and the effective volume ratio of the catalyst relatively decreases, resulting in deterioration in purification performance, increase in pressure loss, and the like.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an exhaust purification device for an internal combustion engine that can improve the effective volume ratio of the catalyst and can be downsized.

(1) A catalyst for purifying exhaust gas is carried on a first honeycomb carrier (for example, first honeycomb carrier 11 described later) provided in an exhaust passage (for example, an exhaust passage 2 described later) of the internal combustion engine. A first exhaust purification unit (for example, a first exhaust purification unit 10 described later);
A second honeycomb carrier (for example, a second honeycomb described later) is provided outside the first exhaust purification section (for example, as described later, so as to surround the outer periphery of the first honeycomb carrier 11). A second exhaust purification unit (for example, a second exhaust purification unit 20 described later) in which a catalyst for purifying exhaust is carried on the carrier 21);
An exhaust flow direction reversing unit (for example, an exhaust flow direction reversing unit 40 described later) that reverses the direction of the exhaust flow that flows out of the first exhaust purification unit and guides it to the second exhaust purification unit,
The exhaust gas purification apparatus for an internal combustion engine, wherein the first honeycomb carrier has a spiral cell structure in which a plurality of first stage cells extend so as to draw a spiral from the exhaust inflow side to the outflow side.

In the exhaust gas purification apparatus for an internal combustion engine of the above (1), the first honeycomb carrier has a spiral cell structure in which a plurality of first stage cells extend so as to draw a spiral from the exhaust inflow side to the outflow side. For this reason, the exhaust gas flowing out of the spirally extending spiral cell structure efficiently flows outward and reverses at the exhaust flow direction reversal unit due to the centrifugal force caused by the swirling, and flows into the second exhaust purification unit.
Therefore, the exhaust gas can be circulated through the second exhaust gas purification unit provided outside the first honeycomb carrier while minimizing the increase in pressure loss due to the reversal of the direction of the exhaust gas flow. Can be shortened. In addition, since the flow path can be lengthened by the spiral, the effective volume ratio of the catalyst can be improved and the size can be reduced.

(2) The first honeycomb carrier has a substantially cylindrical outer shape, and the plurality of first-stage cells have a smaller curvature of the spiral on the exhaust inflow side than on the outflow side. An exhaust purification device for an internal combustion engine.

  In the exhaust gas purification apparatus for an internal combustion engine according to (2) above, particularly in the exhaust gas purification apparatus for an internal combustion engine according to (1), the plurality of first stage cells have the curvature of the spiral on the exhaust inflow side than on the outflow side. Is small. For this reason, the increase in the pressure loss at the site where the pressure loss is usually large, that is, the initial site where the exhaust gas advances straight to the inflow side of the first honeycomb carrier and enters the inside from the end face of the first honeycomb carrier is effectively suppressed. Is done. Therefore, the pressure loss as the whole exhaust gas purification device is reduced.

  (3) The second honeycomb carrier has a substantially hollow cylindrical body (for example, the shape of FIG. 12 to be described later), and the spiral in the swirl direction is reversed from the spiral in the first stage cell. The exhaust gas purification apparatus for an internal combustion engine according to (1) or (2), wherein the plurality of second stage cells have a second spiral cell structure extending in the axial direction of the hollow cylindrical body.

  In the exhaust gas purification apparatus for an internal combustion engine according to (3), particularly in the exhaust gas purification apparatus for the internal combustion engine according to (1) or (2), the second honeycomb carrier has a substantially hollow cylindrical outer shape. The spiral in the first-stage cell has a second spiral cell structure in which a plurality of second-stage cells extend in the axial direction of the hollow cylindrical body so as to draw a spiral in which the turning direction is reversed. As a result, the flow direction of the exhaust flow that has permeated through the plurality of first-stage cells in the first honeycomb carrier and discharged from the outflow end is reversed in the exhaust flow direction reversing section, and the plurality of the plurality of the plurality of first-stage cells in the second honeycomb carrier When turning into the second stage cell from its inflow end and flowing through the plurality of spiral second stage cells in the second honeycomb carrier 21, the swirl direction of the cell changes as viewed along the progress of the exhaust. Without increasing the pressure loss, the exhaust gas can be purified with high efficiency.

  (4) The first honeycomb carrier has a substantially cylindrical outer shape, and the plurality of first-stage cells have a spiral whose curvature is larger in the center side cell of the first honeycomb carrier than the outer side cell. The exhaust emission control device for an internal combustion engine according to any one of (1) to (3), wherein

  In the exhaust gas purification apparatus for an internal combustion engine according to (4) above, in particular, in the exhaust gas purification apparatus for an internal combustion engine according to any one of (1) to (3), the plurality of first-stage cells are arranged on the outer periphery as the cells on the central axis side. It is configured to draw a spiral having a larger curvature than the cell on the side. For this reason, on the outflow side end face of the first honeycomb carrier, the exhaust gas flowing out from the position close to the central axis acts on a relatively strong centrifugal force to change direction, and the second is separated from the outside by a distance. It is possible to move rapidly toward the inflow side of the exhaust purification unit. In other words, the reversal of the exhaust flow direction at the exhaust flow direction reversing portion is performed with high efficiency. The exhaust flowing into the inflow end of the second honeycomb carrier is less likely to be unevenly distributed, and the reduction in the effective volume ratio of the catalyst is suppressed. As a result, the exhaust purification performance as the exhaust purification device is maintained at a high level.

  (5) The first honeycomb carrier has a convex shape in which the shape of the outflow side end face (for example, an outflow end 111b described later) protrudes in the exhaust outflow direction toward the center side from the outer peripheral side. The exhaust gas purification device for an internal combustion engine according to any one of the above.

  In the exhaust gas purification apparatus for an internal combustion engine according to (5), in particular, in the exhaust gas purification apparatus for an internal combustion engine according to any one of (1) to (4), the outflow side of the first honeycomb carrier in the first exhaust gas purification unit. The shape of the end surface is a convex shape that projects in the outflow direction of the exhaust toward the center side rather than the outer peripheral side. For this reason, it is avoided that the exhaust from each of the cells blown outward as a swirl flow from the outflow side end face through the plurality of first stage cells of the first honeycomb carrier is dispersed radially and interferes with each other. . Accordingly, the exhaust gas flowing out from the outflow side end face of the first honeycomb carrier of the first exhaust gas purification unit efficiently passes through the exhaust gas flow direction reversing unit, and the second honeycomb carrier (a plurality of the second exhaust gas purification units) on the outer side. The second stage cell). As a result, the pressure loss of the entire exhaust gas purification device is reduced.

  (6) In the internal combustion engine according to (5), the first honeycomb carrier has a concave shape in which the shape of an inflow side end surface (for example, an inflow end 111a described later) is recessed in the exhaust inflow direction toward the center side from the outer peripheral side. Exhaust purification device.

  In the exhaust gas purification apparatus for an internal combustion engine of (6) above, particularly in the exhaust gas purification apparatus of the internal combustion engine of (5) above, the shape of the inflow side end face of the first honeycomb carrier in the first exhaust gas purification unit is more than the outer peripheral side. The central axis is a concave shape that is recessed in the exhaust inflow direction. That is, as described in (5) above, even if the shape of the outflow side end face of the first honeycomb carrier is a convex shape that protrudes in the exhaust outflow direction from the outer peripheral side toward the central axis side, The shape of the end face on the inflow side of one honeycomb carrier is a concave shape that is recessed in the inflow direction of exhaust toward the center side rather than the outer peripheral side. For this reason, there is no difference in the channel length between the channel close to the center of the first honeycomb carrier and the channel separated from the center. Therefore, there is no difference in the pressure loss of each flow path, and the exhaust distribution is not biased. As a result, a decrease in the effective volume ratio of the catalyst in the first honeycomb carrier is suppressed.

  (7) In the first honeycomb carrier, the cell walls that define the first stage cell have concentric peripheral wall portions (for example, concentric peripheral wall portions S61 and S62 described later) in a cross-sectional view orthogonal to the central axis. S63, S64,... S6n) and radial side wall portions (for example, radial side wall portions R61, R62, R63, R64,... R6m, which will be described later), any one of (2) to (6) Engine exhaust purification system.

  In the exhaust gas purification apparatus for an internal combustion engine according to (7), in particular, in the exhaust gas purification apparatus for an internal combustion engine according to any one of (2) to (6), the first honeycomb carrier partitions each first stage cell. The cell wall has a concentric peripheral wall portion and a radial side wall portion in a cross-sectional view orthogonal to the central axis. For this reason, even if the outer shape of the first honeycomb carrier is a substantially cylindrical body, the cells at the position facing the outer peripheral surface are not narrowed according to the curvature of the outer periphery, and the cross-sectional area is ensured. Therefore, each cell (first stage cell) functions effectively regardless of the position in the cross section of the first honeycomb carrier. As a result, a decrease in the effective volume ratio of the catalyst in the first honeycomb carrier is avoided.

  (8) In the first honeycomb carrier, the cell walls defining the first stage cells have concentric peripheral wall portions in a cross-sectional view orthogonal to the central axis (for example, peripheral wall portions S71, S72, S73, and S74 described later). ,... S7n) and side wall portions (for example, side wall portions D11, D12, D13,..., D21, D22, D23,..., D31, D32, D33,... Described later) in a direction intersecting the concentric peripheral wall portion. The peripheral wall portion and the side wall portion are arranged so that the cross-sectional areas of the respective first stage cells (for example, cells Q11, Q22, Q33,... Described later) are equal to each other (6) to (6) The exhaust gas purification device for an internal combustion engine according to any one of the above.

  In the exhaust gas purification apparatus for an internal combustion engine according to (8), in particular, in the exhaust gas purification apparatus for an internal combustion engine according to any one of (2) to (6), the first honeycomb carrier partitions each first stage cell. The cell wall has a concentric peripheral wall portion and a side wall portion in a direction intersecting the concentric peripheral wall portion in a cross-sectional view orthogonal to the central axis, and the cross-sectional area of each cell is equal in the peripheral wall portion and the side wall portion. Has been placed. For this reason, even if the outer shape of the first honeycomb carrier is a substantially cylindrical body, the pressure loss is the same in the cell at the position facing the outer peripheral surface and the cell in the vicinity of the central axis. Therefore, there is no bias in the exhaust distribution. As a result, a decrease in the effective volume ratio of the catalyst in the first honeycomb carrier is suppressed.

  (9) In the first honeycomb carrier, the cell walls defining the first stage cells have concentric peripheral wall portions (for example, peripheral wall portions S81, S82, S83, and S84 described later) in a cross-sectional view orthogonal to the central axis. ,... S8n) and side wall portions (for example, side wall portions D11, D12, D13,..., D21, D22, D23,..., D31, D32, D33,. The peripheral wall portion and the side wall portion are arranged so that the cross-sectional area of the first stage cell (for example, each cell Q11, Q22, Q33,... Described later) is larger toward the outer peripheral side than the central axis side (2 ) To (6), the exhaust gas purification apparatus for an internal combustion engine.

  In the exhaust gas purification apparatus for an internal combustion engine according to (9), in particular, in the exhaust gas purification apparatus for an internal combustion engine according to any one of (2) to (6), the first honeycomb carrier defines the first stage cell. The cell wall has a concentric peripheral wall portion in a cross-sectional view orthogonal to the central axis and a side wall portion in a direction intersecting with the peripheral wall portion, and the peripheral wall portion and the side wall portion have a cross-sectional area of the first stage cell on the central axis side. It arrange | positions so that it may become large toward the outer peripheral side. For this reason, the pressure loss is smaller in the cell at the position facing the outer peripheral surface of the first honeycomb carrier which is a substantially cylindrical body than the cell in the vicinity of the central axis. Therefore, even when the diameter of the exhaust inlet is narrowed down so that the exhaust purification device can be smoothly connected to the internal combustion engine, the exhaust from the internal combustion engine is appropriately dispersed also on the outer peripheral side of the first honeycomb carrier. To do. As a result, the decrease in the effective volume ratio of the catalyst in the first honeycomb carrier is suppressed, and the overall pressure loss is also suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the exhaust gas purification apparatus of the internal combustion engine which can improve the effective volume ratio of a catalyst and can be reduced in size can be embodied.

1 is a cross-sectional perspective view of an embodiment of an exhaust gas purification apparatus for an internal combustion engine of the present invention. It is a schematic diagram showing the partial side cross section of the exhaust gas purification device of the internal combustion engine of FIG. It is a schematic diagram showing the partial cross section of the exhaust gas purification device of the internal combustion engine of FIG. FIG. 4 is a schematic diagram showing an aspect of an exhaust flow path constituted by cells in the first honeycomb carrier in FIGS. 1, 2, and 3. FIG. 5 is a schematic diagram showing a cross-sectional view of the exhaust flow path of FIG. 4. FIG. 4 is a schematic view showing another aspect of an exhaust flow path constituted by cells in the first honeycomb carrier in FIGS. 1, 2, and 3. FIG. 4 is a view for explaining still another aspect of an exhaust passage constituted by cells in the first honeycomb carrier in FIGS. 1, 2, and 3. FIG. 8 is a diagram showing a part in the first honeycomb carrier illustrating details of an exhaust flow path described by FIG. 7. FIG. 9 is a perspective view showing a part in the first honeycomb carrier represented by FIG. 8 in detail. FIG. 2 is a schematic diagram showing an example of a spiral cell structure in a first honeycomb carrier of the exhaust gas purification apparatus for an internal combustion engine of FIG. FIG. 6 is a schematic view showing another example of the spiral cell structure in the first honeycomb carrier of the exhaust gas purification apparatus for the internal combustion engine of FIG. FIG. 7 is a perspective view of one embodiment of the second honeycomb carrier in FIGS. 1, 2, 3, and 6. FIG. 13 is a schematic diagram illustrating a spiral cell structure in the second honeycomb carrier of FIG. 12. FIG. 8 is a schematic diagram showing a main part of still another aspect of the exhaust gas purification apparatus for an internal combustion engine shown in FIGS. 3, 4, 6, and 7. FIG. 14B is a schematic diagram for comparatively explaining the operation when the mode as in FIG. 14A is not adopted. FIG. 7 is a schematic diagram showing a partial side cross-section of still another aspect of the exhaust gas purification apparatus for an internal combustion engine shown in FIGS. 1, 2, and 3. FIG. 16 is a schematic diagram for explaining the operation of the exhaust gas purification apparatus for the internal combustion engine of FIG. 15. It is a schematic diagram showing the partial cross section of the exhaust gas purification device of FIG. FIG. 16 is a schematic view partially showing a portion near the outer peripheral surface of the first honeycomb carrier of the exhaust purification device of FIG. 15 in a sectional view.

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

FIG. 1, FIG. 2, and FIG. 3 are diagrams showing an embodiment of an exhaust gas purification device for an internal combustion engine (hereinafter, referred to as an exhaust gas purification device as appropriate) of the present invention.
1 is a cross-sectional perspective view of an embodiment of an exhaust gas purification apparatus for an internal combustion engine of the present invention, FIG. 2 is a schematic diagram showing a partial side cross section of the exhaust gas purification apparatus for the internal combustion engine of FIG. 1, and FIG. It is a schematic diagram showing the partial cross section of this exhaust gas purification device.
1, 2, and 3, the corresponding parts are denoted by the same reference numerals.
1 and 2, the left side is the upstream side of the exhaust flow in the exhaust passage 2 (shown by the broken line in FIG. 2) of the internal combustion engine, and the right side is the downstream side of the exhaust flow.

  Note that the upstream and downstream directions in the above are the flow directions when the entire exhaust gas purification apparatus is viewed from the outside. Specifically, as will be described later, inside the exhaust purification device, the exhaust flow in the first exhaust purification unit 10 is a spiral flow along the above-mentioned direction as a whole, but the second exhaust purification unit In 20, the direction is opposite to the above. That is, the flow in the second exhaust purification unit 20 as a whole is in the direction opposite to the above, and the flow is reversed again downstream thereof to become the flow direction when the entire exhaust purification device is viewed from the outside.

A first honeycomb carrier 11 whose outer shape forms a substantially cylindrical body is provided in the first exhaust purification unit 10, and a plurality of cells that are a plurality of cells serving as exhaust passages are provided in the first honeycomb carrier 11. The first stage cell is extended. Here, a catalyst for purifying exhaust gas is carried.
In the following description, the first stage cell is appropriately referred to as a cell.

In FIG. 2, a side cross section of the exhaust emission control device 1 is drawn in the upper part of the central axis X of the first honeycomb carrier 11 that forms a substantially cylindrical body.
As apparent from the partial cross section of FIG. 3, an annular second exhaust purification unit 20 is provided so as to surround the outer periphery outside the first honeycomb carrier 11. A second honeycomb carrier 21 having a substantially hollow cylindrical body, that is, an annular block body, is provided in the second exhaust purification section 20, and the second honeycomb carrier 21 also purifies exhaust gas. The catalyst is supported.

  The exhaust purification device 1 including the first exhaust purification unit 10 and the second exhaust purification unit 20 forms an outermost peripheral surface around the central axis X on the outer peripheral side of the second exhaust purification unit 20, for example, It has an outer shell portion 31 made of a stainless steel plate or the like. In the outer shell portion 31, a carrier partition wall portion 32 that forms a partition wall between the first honeycomb carrier 11 and the second honeycomb carrier 21 is provided. Further, an inlet side connecting portion 33 extending upstream of the exhaust flow so that the outer shell portion 31 is connected to an internal combustion engine (not shown) side, and a downstream side in the exhaust passage 2 for discharging the exhaust flow downstream. An outlet side connecting portion 34 whose diameter is narrowed so as to be connected to a pipe (not shown) is formed.

  In the exhaust gas purification apparatus 1, the untreated exhaust gas 3a (shown by a white arrow in FIG. 2) from the inlet side connection portion 33 is the left end side of the first honeycomb carrier 11 in FIGS. Exhaust gas 3b (shown by a white arrow in FIG. 2) that flows into the exhaust inflow side (inflow end 11a side) and purified by the exhaust gas purification device 1 is discharged from the outlet side connection portion 34. .

  Referring to FIGS. 1 and 2, in the outer shell portion 31, the second honeycomb carrier 21 is formed from the first honeycomb carrier 11 from the exhaust outflow side (outflow end 11 b side) which is the right end side in the drawing. In the figure, there is provided an exhaust flow direction reversing section 40 for changing the direction of the exhaust flow to the exhaust inflow side (inflow end 21a side) which is the right end side.

  The exhaust flow direction reversing part 40 has a counter plate part 41 and an annular plate part 42. The opposing plate portion 41 is opposed to the outflow end 11b of the first honeycomb carrier 11 and the inflow end 21a of the second honeycomb carrier 21 with a certain distance therebetween, and the exhaust gas flowing out from the outflow end 11b is in the direction of the central axis X This is a virtual disk-shaped portion that prevents the flow of the liquid and flows in the outer circumferential direction. The annular plate portion 42 extends forward (leftward in the figure) while drawing an arc from the entire periphery of the outer periphery of the opposing plate portion 41 in a side view (FIG. 2), and the outer periphery of the second honeycomb carrier 21 is disposed at the outflow end 21 b. It is the part which surrounds.

  Between the opposed plate portion 41 of the exhaust flow direction reversing portion 40 and the outflow end 11b of the first honeycomb carrier 11 and the inflow end 21a of the second honeycomb carrier 21, the exhaust gas flowing out from the outflow end 11b is inflow end 21a. A diverting flow path 41a is formed through which the exhaust flow is circulated so as to change the direction so as to flow into.

  Further, between the annular plate portion 42 of the exhaust flow direction reversing portion 40 and the outer shell portion 31 described above, the exhaust gas flowing out from the outflow end 21b of the second honeycomb carrier 21 is rearward (right side in the figure). A discharge flow path 42a is formed to discharge toward the outlet side connection portion 34.

  As is apparent with reference to FIG. 3 as well, in a cross-sectional view, the second honeycomb carrier 21 has an annular shape that surrounds the outer peripheral side of the first honeycomb carrier 11 in a substantially cylindrical body via a carrier partition wall portion 32. It is a block body. Further, the annular plate portion 42 surrounds the second honeycomb carrier 21 from the outer peripheral side. As described above, the discharge flow path 42 a is formed between the annular plate portion 42 and the outer shell portion 31.

Next, the exhaust gas flow path constituted by the cells in the first honeycomb carrier 11 described with reference to FIGS. 1, 2, and 3 will be described with reference to FIGS. 4 and 5. FIG.
FIGS. 4 and 5 show the flow of exhaust gas constituted by a plurality of first stage cells which are cells in the first honeycomb carrier 11 of the exhaust gas purification apparatus of the internal combustion engine of FIGS. 1, 2 and 3. It represents the road conceptually.
FIG. 4 is a schematic view conceptually showing a side view of an exhaust passage typically constituted by one cell among a plurality of first-stage cells in the first honeycomb carrier 11. FIG. 5 conceptually shows a cross-sectional view of the exhaust passage in FIG.
4 and 5, the same reference numerals are given to corresponding parts in FIGS. 1, 2, and 3.

  As easily understood with reference to FIGS. 4 and 5, the first honeycomb carrier 11 arranged inside the carrier partition wall portion 32 described above with reference to FIGS. 1, 2, and 3. When attention is paid to one cell 110 representatively among the plurality of cells (first stage cells) in the cell, this cell 110 is the exhaust inflow side (inflow end 11a side) of the first honeycomb carrier 11. The cell has a spiral cell structure in which the cell extends so as to draw a spiral toward the outflow side (outflow end 11b side). In the drawing, one cell 110 is representatively drawn, but each cell of the first honeycomb carrier 11 has a structure extending in a spiral shape similar to the cell 110.

  On the other hand, the cells in the second honeycomb carrier 21 are, as will be described in detail later with reference to FIG. 12 and FIG. 13, the spiral cell structure as in the first honeycomb carrier 11 is the turning direction around the central axis X. Has a reversed helical cell structure. That is, the second honeycomb carrier 21 has a spiral cell structure having a pitch opposite to the spiral pitch of each cell in FIG. 4 (typically, the cells 110 are illustrated).

Next, the operation of the exhaust emission control device 1 described with reference to FIGS. 1, 2, 3, 4, and 5 will be described.
Exhaust gas 3 a (FIG. 2) from the internal combustion engine (not shown) side flows into the first honeycomb carrier 11 from the inflow end 11 a side of the first honeycomb carrier 11. Specifically, the exhaust gas 3 a flows into each cell of the above-described spiral cell structure in the first honeycomb carrier 11.
As described above, the exhaust gas flowing into each cell of the above-described spiral cell structure in the first honeycomb carrier 11 becomes a swirl flow while being purified by the catalyst while proceeding through the spiral flow path. Outflow end 11b (that is, outflow ends of a plurality of first stage cells).

Exhaust gas flowing out from the spirally extended cell (represented by one cell 110 in FIG. 4) is efficiently changed in the flow direction by the exhaust flow direction reversing unit 40 by the centrifugal force caused by the swirling, and is discharged into the second exhaust gas. It flows into the purification unit 20.
Specifically, the exhaust gas flowing out from the outflow end 11b of the first honeycomb carrier 11 does not go straight in the normal direction of the outflow end 11b due to the centrifugal force due to the swirling, and forms a substantially cylindrical body. Deflection toward the outer peripheral side of the honeycomb carrier 11. That is, it tends to advance in the radial direction from the time when it flows out from the outflow end 11b.

In the exhaust flow direction reversing unit 40, as described above, the exhaust flow having a tendency to be deflected from the beginning of flowing out from the outflow end 11b is converted into the second exhaust purification unit 20 on the outer peripheral side at the conversion flow path 41a. It is possible to efficiently lead to the inflow end 21a of the second honeycomb carrier 21 (that is, the inflow ends of a plurality of second stage cells described later).
For this reason, the increase in the pressure loss due to the change in the direction of the exhaust flow in the exhaust flow direction reversing unit 40 can be kept to a minimum.

  In the exhaust emission control device 1 of the present embodiment, the second exhaust gas in which the flow direction (from left to right in FIG. 2) is different from that of the first honeycomb carrier 11 after solving the problem of pressure loss as described above. A configuration is adopted in which exhaust gas is circulated through the purification section (the distribution direction is reversed from right to left in FIG. 2). In this way, the layout having a part that reverses the exhaust flow in the middle is adopted, so the overall length of the apparatus is significantly reduced compared to the exhaust purification apparatus as a whole that has a layout in which the exhaust inflow side to the outflow side are linearly connected. Is done. Therefore, the exhaust purification device 1 that is small in size and has little pressure loss and excellent purification performance is realized.

Next, another aspect of the exhaust emission control device 1 will be described with reference to FIG.
FIG. 6 is a schematic diagram showing another aspect of the exhaust gas purification apparatus for the internal combustion engine of FIG. 1, and in particular, shows each flow path of exhaust gas constituted by two typical cells in the first honeycomb carrier 11. It is expressed conceptually. These two cells are exaggerated in size for convenience of explanation.
In FIG. 6, the same reference numerals are given to the corresponding parts in FIG. 1, FIG. 2 and FIG. 3 and FIG. 4 and FIG. 5 described above.

  The difference between the embodiment of FIG. 6 and the embodiment of FIG. 4 described above lies in the difference in the turning speed of the spiral cell. That is, a plurality of spiral cells in the embodiment of FIG. 6 are formed, and the plurality of spiral cells are closer to the center axis X of the first honeycomb carrier 11 (the spiral cell 111 in the figure). It is configured so as to draw a spiral having a relatively larger curvature than a cell separated from X (the spiral cell 112 in the figure).

  In the aspect of FIG. 6, at the outflow end 11 b of the first honeycomb carrier 11, the exhaust gas flowing out from a position close to the central axis X changes its direction by applying a relatively strong centrifugal force, and the second exhaust purification unit 20. The inflow end 21a of the second honeycomb carrier 21 which is the inflow side of the second can be rapidly moved. For this reason, even if the distance to the inflow end 21a of the second honeycomb carrier 21 is relatively long, there is no delay before reaching the inflow end 21a, and the direction of the exhaust flow in the exhaust flow direction reversing unit 40 Conversion is performed with high efficiency. Therefore, the exhaust gas flowing into the inflow end 21a of the second honeycomb carrier 21 is unlikely to be unevenly distributed, and a decrease in the effective volume ratio of the catalyst is suppressed. As a result, the exhaust purification performance as the exhaust purification device 1 is maintained at a high level.

Next, still another aspect of the exhaust emission control device 1 will be described with reference to FIGS. 7, 8, and 9.
FIG. 7 is a view for explaining still another aspect of the exhaust flow path constituted by the cells in the first honeycomb carrier in FIGS. 1, 2, and 3, and FIG. 8 is described with reference to FIG. FIG. 9 is a perspective view showing a part in the first honeycomb carrier shown in FIG. 8 in detail, and FIG. 9 is a perspective view showing a part in the first honeycomb carrier in detail.

  The horizontal axis in FIG. 7 is the distance in the central axis X direction from the inflow end 11a (denoted as the inlet in the figure) of the first honeycomb carrier 11 to the outflow end 11b (denoted as the outlet in the figure). (Denoted as a distance in the length direction). The vertical axis represents the rotation angle per unit length in the aforementioned spiral cell. That is, the vertical axis corresponds to the steepness of the spiral.

In still another aspect of the exhaust emission control device 1, as shown in FIG. 7, the cells in the spiral cell structure in the first honeycomb carrier 11 are spirally swirled at the inflow end 11 a of the first honeycomb carrier 11. Is the loosest, and the spiral turns sharply toward the outflow end 11b.
In other words, the spiral cell has a relatively smaller spiral curvature on the exhaust inflow side than on the outflow side.
For this reason, there is usually an increase in pressure loss at the site where the pressure loss is large, that is, the initial site where the exhaust gas advances straight to the inflow side of the first honeycomb carrier 11 and enters the inside from the inflow end 11a of the first honeycomb carrier 11. Effectively suppressed. Accordingly, the pressure loss of the exhaust purification device 1 as a whole is reduced.

Next, a specific example of the spiral cell structure described with reference to FIG. 7 will be described in more detail.
As described above, the individual cells in the first honeycomb carrier 11 are from the inflow end 11a to the outflow end 11b of the first honeycomb carrier 11 like the cell 110 in FIG. 4 and the cells 111 and 112 in FIG. It is formed in a spiral shape.

In the spiral cell structure of the present invention, a plurality of spiral cells in the first honeycomb carrier 11 have a small turning radius in the vicinity of the center axis X of the carrier, and a turning radius in the vicinity of the outer periphery of the carrier has a large diameter. It is constructed by concentrically forming multiple layers in the radial direction.
Regarding the concentric radial layers, it is convenient for visual understanding to refer to FIG. 10 described later.

Further, among the plurality of concentric multilayer cells described above, the plurality of spiral cells corresponding to the same layer have a common turning radius and a position from the inflow end 11a of the first honeycomb carrier 11 toward the outflow end 11b (that is, , A position in the direction of the central axis X) is in a form in which the phase of the rotation is sequentially shifted. As a result, when the first honeycomb carrier 11 is represented in a cross-sectional view orthogonal to the central axis X, a plurality of first-stage cells cross-sectionally aligned in the circumferential direction appear.
As described above, referring to FIG. 10, which will be described later, is also convenient for visual understanding of the appearance of the cross-sections of the plurality of first-stage cells aligned in the circumferential direction.

  Next, a plurality of first-stage cells are formed in the form in which the phases relating to the position in the central axis X direction are different as described above while corresponding to the same layer among the concentric multilayer cells and having the same turning radius. The manner in which this is done will be described below with reference to FIGS. 8 and 9. FIG.

FIG. 9 is a perspective view showing in detail the spiral cell structure of the virtual cylindrical portion 11v in the vicinity of the central axis X with the central axis X in the first honeycomb carrier 11 shown in FIG.
FIG. 9 shows the elements defining the cell Crc with respect to one cell Crc in the spiral cell structure of the portion 11v in the vicinity of the central axis X in the first honeycomb carrier 11 described above.
FIG. 9 shows a state in which the peripheral wall portion on the outer peripheral side of the cell Crc is removed, so that the cell Cr-1, c one layer inside the cell Crc is recognized at the outflow end 11b.
The suffix r in Crc represents the number of the cell from the outermost peripheral side to the inner side. Further, the suffix c represents the number of cells divided by the peripheral wall portion in the circumferential direction from an appropriate reference position when viewed in a predetermined cross section.

In FIG. 9, only the cell side wall Hrc, which is one of a pair of adjacent spiral cell side walls, is shown in a state in which the peripheral wall portion on the outer peripheral side of the cell Crc is removed and the inside is visually observed.
The suffix r in Hrc represents the number of cells partitioned by the peripheral wall portion from the outermost peripheral side to the inner side. Further, the suffix c represents the number of cells divided by the peripheral wall portion in the circumferential direction from an appropriate reference position when viewed in a predetermined cross section.

The cell Crc includes a pair of peripheral wall portions Pr and Pr-1 corresponding to two cylindrical cylinders adjacent to each other coaxially around the central axis X, and a pair of cell side walls Hrc and Hrc-1 (for convenience of explanation in FIG. 9). Only Hrc is shown).
The suffix r in Pr represents the number of the one peripheral wall portion defining the cell Crc inward from the outermost peripheral side of the carrier partition wall portion 32 (see FIGS. 2, 3, and 6).
The peripheral wall portion Pr-1 is a peripheral wall portion on the outer peripheral side of the cell Crc. In FIG. 9, the inner side thereof is removed as described above so as not to be seen.

In FIG. 9, the section of each cell of the portion 11v near the central axis X is visually observed at the outflow end 11b of the first honeycomb carrier 11. Focusing on the outflow end 11b, for the cell Cr-1, c on the inner layer side of one layer with respect to the one cell Crc described above, a pair of peripheral wall portions and cell side walls surrounding the four circumferences are visually recognized.
As described above with reference to FIG. 7, the spiral cells of this example are characterized in that the spiral curvature is relatively smaller on the exhaust inflow side than on the outflow side.

This point will be described by paying attention to the cell side wall Hrc of the cell Crc as a representative.
For convenience of explanation, the cell side wall Hrc in FIG. 9 is divided into three parts with different positions along the central axis X of the first honeycomb carrier 11. That is, the portion close to the inflow end 11a side is referred to as Hrc-1, the portion corresponding to the middle between the inflow end 11a and the outflow end 11b is referred to as Hrc-2, and the portion close to the outflow end 11b side is referred to as Hrc-3.
As is noticeable with reference to FIG. 9, the cell side wall Hrc is formed so that the fins are spirally wound around the peripheral wall portion Pr, and the entire side wall Hrc is directed from the inflow end 11a toward the outflow end 11b. In particular, the spiral curvature tends to increase gradually.
That is, the curvature of the spiral is the smallest in the Hrc-1 portion (ie, the turning is slow), the curvature of the spiral is moderate in the Hrc-2 portion, and the spiral curvature is the most in the Hrc-3 portion. Is large (ie, the turn is steep).

The cell Crc is partitioned on both sides by the cell side wall Hr, c + 1 (not shown) paired with the cell side wall Hrc as described above, and a spiral is formed at the inflow end 11a of the first honeycomb carrier 11. The spiral is steepest as it goes to the outflow end 11b.
For this reason, with regard to the flow of exhaust gas in the cell, the pressure loss in the Hrc-1 portion where the pressure loss is usually large is suppressed, while the Hrc-3 portion in the vicinity of the outflow end 11b is a portion that makes a sharp turn, Exhaust obtains a relatively strong centrifugal force, causing a rapid turn.
That is, it is possible to rapidly head to the inflow end 21a of the second honeycomb carrier 21 that is the inflow side of the second exhaust purification unit 20 in FIGS. For this reason, the direction change of the exhaust flow until it reaches this inflow end 21a is performed with high efficiency. Therefore, the exhaust purification performance as the exhaust purification device 1 is maintained at a high level.

Next, one aspect of the spiral cell structure in the first honeycomb carrier of the exhaust purification device 1 will be described with reference to FIG.
FIG. 10 is a schematic view showing an example of a spiral cell structure in the first honeycomb carrier of the exhaust emission control device in a cross section, and in particular, a portion near the outer peripheral surface of the first honeycomb carrier 11 is partially center axis X The cross-sectional view is orthogonal to

  Referring to FIG. 10, in the first honeycomb carrier 11, the cell wall defining each cell has a concentric peripheral wall portion and a radial wall portion in a cross-sectional view. That is, in FIG. 10, the concentric peripheral wall portions are arranged in order from the wall portion immediately below the above-described carrier partition wall portion 32 toward the inside (center axis X) at the outermost periphery in order of S61, S62, S63, S64,. A predetermined number of concentric peripheral wall portions are formed as in S6n. Further, the wall portion extending in the radial direction from the central axis X forms a radial cell side wall such as R61, R62, R63, R64,... R6m at a predetermined interval in the circumferential direction.

Each cell is divided into four by the concentric peripheral wall portion and the radial cell side wall. In FIG. 10, the three cells C12, C22, and C32 are typically given reference numerals.
The cell C12 is located on the outermost peripheral side of the first honeycomb carrier 11, and is partitioned by two concentric peripheral wall portions S61 and S62 and two radial cell side walls R62 and R63.
Similarly, the cell C22 has the same position in the circumferential direction as the cell C12, and one cell C22 is located on the inner circumferential side in the radial direction. The cell C22 is partitioned by two concentric peripheral wall portions S62 and S63 and two radial cell side walls R62 and R63.
Furthermore, the cell C32 has the same position in the circumferential direction as the cell C22, and one cell C32 is located on the inner circumferential side in the radial direction. The cell C32 is partitioned by two concentric peripheral wall portions S63 and S64 and two radial cell side walls R62 and R63.

In the first honeycomb carrier 11 of FIG. 10, even if the outer shape is a substantially cylindrical body, the cell (C12) at the position facing the outer peripheral surface is not narrowed and the cross-sectional area is secured. Therefore, regardless of whether the position of the first honeycomb carrier 11 in the cross section is the outer peripheral side or the inner peripheral side, each cell has a cross-sectional area of a certain level or more and functions effectively. As a result, a decrease in the effective volume ratio of the catalyst in the first honeycomb carrier is avoided.
In the case of the cell described above with reference to FIG. 7, FIG. 8, and FIG. 9, the embodiment shown in FIG. In this case, in addition to the effects in the case of FIG. 7, FIG. 8, and FIG. 9, the effect in the case of adopting the aspect of FIG.

Here, another aspect of the spiral cell structure in the first honeycomb carrier of the exhaust emission control device 1 will be described with reference to FIG.
FIG. 11 is a schematic view showing another example of the spiral cell structure in the first honeycomb carrier of the exhaust purification device in cross section, and in particular, a partial cross section about a portion near the outer peripheral surface of the first honeycomb carrier 11. Expressed visually.
In FIG. 11, the part having the curvature is drawn linearly in a simple manner.

  When the first honeycomb carrier 11 is viewed in cross-section with respect to the embodiment of FIG. 11, the cell walls defining each cell have concentric peripheral wall portions and cell side walls in a direction intersecting with the concentric peripheral wall portions. . That is, in FIG. 11, the concentric peripheral wall portions are arranged in order from the peripheral wall portion immediately below the above-described carrier partition wall portion 32 toward the inside (central axis X) at the outermost periphery in order of S71, S72, S73, S74,. A predetermined number of concentric peripheral walls are formed as in S7n. In this respect, the configuration of FIG. 11 is the same configuration as the configuration of FIG. 10, but in the configuration of FIG. 11, the cell continuously extends in the radial direction from the central axis X as in the configuration of FIG. 10. The configuration is different in that there is no side wall.

  That is, in the embodiment of FIG. 11, the cell walls in the embodiment of FIG. 10 continuously extending in the radial direction from the central axis X are replaced with concentric peripheral wall portions S71, S72, S73, S74,. Cell side walls D11, D12, D13,..., D21, D22, D23,..., D31, D32, D33,. The feature in the embodiment of FIG. 11 is that the cross-sectional areas of the cells Q11, Q22, Q33,... Partitioned by the concentric peripheral wall portion and the cell side wall in the direction intersecting this are equal.

Here, the three cells Q11, Q22, and Q33 are typically considered. The cell Q11 is partitioned by two concentric peripheral wall portions S71 and S72 and two cell side walls D11 and D12. The cell Q22 is partitioned by two concentric peripheral wall portions S72 and S73 and two cell side walls D21 and D22. Furthermore, the cell Q33 is partitioned by two concentric peripheral wall portions S73 and S74 and two cell side walls D31 and D32.
As described above, the cells Q11, Q22, Q33,... Have the same cross-sectional area. In other words, the concentric peripheral walls S71, S72, S73, S74,... S7n and the cell side walls D11, D12, D13. ,..., D21, D22, D23,..., D31, D32, D33,... Are arranged so that the cross-sectional areas of the respective cells Q11, Q22, Q33,.

  In the first honeycomb carrier 11 of FIG. 11, the cross-sectional areas of the cells are equal. For this reason, even if the outer shape of the first honeycomb carrier 11 is a substantially cylindrical body, the pressure loss is the same for the cells at the position facing the outer peripheral surface and the cells near the central axis. Therefore, there is no bias in the distribution of exhaust over substantially the entire cross section of the first honeycomb carrier 11. As a result, a decrease in the effective volume ratio of the catalyst in the first honeycomb carrier 11 is suppressed.

Next, one embodiment of the second honeycomb carrier in FIGS. 1, 2, 3, and 6 will be described with reference to the drawings.
FIG. 12 is a perspective view of one embodiment of the second honeycomb carrier in FIGS. 1, 2, 3, and 6.
FIG. 13 is a schematic diagram showing a helical cell structure in the second honeycomb carrier of FIG.
As is easily understood with reference to FIG. 12, the second honeycomb carrier 21 has a substantially hollow cylindrical body, that is, an annular block body. From the inflow end 21 a described above with reference to FIG. 1. Exhaust gas flows to the outflow end 21b. The positional relationship between the inflow end 21a and the outflow end 21b in the direction of the central axis X is such that the position of the inflow end 11a and the outflow end 11b of the first honeycomb carrier 11 arranged concentrically inside the second honeycomb carrier 21. The relationship is an inverted relationship.

  In the spiral cell structure in this example, a plurality of second-stage cells that are a plurality of spiral cells are concentrically formed in a radial multilayer in the second honeycomb carrier 21. However, according to circumstances, the spiral cell structure of the second honeycomb carrier 21 may be constituted by one layer of spiral cells.

  Further, the plurality of spiral cells corresponding to the same layer among the above-described concentric multilayer cells have the same turning radius and the position from the inflow end 21a of the second honeycomb carrier 21 toward the outflow end 21b. The turning phase is shifted sequentially. As a result, when the second honeycomb carrier 21 is represented in a cross-sectional view orthogonal to the central axis X, a plurality of second-stage cells cross-sectionally aligned in the circumferential direction appear.

  Next, referring to FIG. 13, a plurality of the first and second cells are arranged in different forms with respect to the position in the central axis X direction while corresponding to the same layer among the above-described concentric multilayer cells and having a common turning radius. The manner in which the two-stage cell is formed will be described below.

FIG. 13 shows elements defining the cell ECrc with respect to one cell ECrc in the spiral cell structure formed in the second honeycomb carrier 21 of FIG.
The suffix r in ECrc represents the number of cells partitioned by the peripheral wall portion from the outermost peripheral side to the inner side. Further, the suffix c represents the number of cells divided by the peripheral wall portion in the circumferential direction from an appropriate reference position when viewed in a predetermined cross section.

In FIG. 13, only the cell side wall EHrc, which is one of a pair of adjacent spiral cell side walls, is shown in a state where the outer peripheral side wall portion of the cell ECrc is removed and the inside is visually observed.
The suffix r in EHrc indicates the number of cells partitioned by the peripheral wall portion from the outermost peripheral side to the inner side. Further, the suffix c represents the number of cells divided by the peripheral wall portion in the circumferential direction from an appropriate reference position when viewed in a predetermined cross section.

The cell ECrc includes a pair of peripheral wall portions EPr and EPr-1 which are corresponding portions of a pair of cylinders having a common axis, and a cell side wall cell side wall EHrc and EHrc-1 which are a pair of cell side walls (in FIG. 13, for convenience of explanation). The four sides are partitioned by the cell side wall EHrc.
The suffix r in EPr indicates the number of the one peripheral wall section defining the cell ECrc from the outermost peripheral side to the inner side of the carrier partition wall section 32.
The peripheral wall portion EPr-1 is a peripheral wall portion on the outer periphery side of the cell ECrc, and in FIG. 13, the inner side thereof is removed as described above so as to be invisible.

With reference to FIG. 13, description will be given focusing on one cell side wall EHrc as a representative of a pair of cell side walls EHrc and EHrc-1 (the latter is not shown) of the cell ECrc.
The cell side wall EHrc in FIG. 13 is formed so that the fin is spirally wound around the peripheral wall portion EPr. In addition, from the inflow end 21a side to the outflow end 21b side, the swirl direction around the central axis X is reversed with respect to the cell side wall Hrc of the cell Crc in the first honeycomb carrier 11 described above. Is formed.

That is, in the spiral cell in the second honeycomb carrier 21, the turning direction around the spiral central axis X is the turning direction around the spiral central axis X in the spiral cell in the first honeycomb carrier 11. It is formed in the reversed direction.
Thereby, the exhaust flow which permeate | transmitted the some 1st stage cell in the 1st honeycomb support | carrier 11, and was discharged from the outflow end 11b flows in the exhaust flow direction inversion part 40 already mentioned with reference to FIG.1 and FIG.2. Is reversed, flows into the plurality of second stage cells in the second honeycomb carrier 21 from the inflow end 21a, and flows through the plurality of spiral second stage cells in the second honeycomb carrier 21. The cell turning direction as viewed along the progress of the exhaust gas does not change, and the increase in pressure loss is suppressed to a minimum, so that the exhaust gas can be purified with high efficiency.

  In the spiral cell structure (second spiral cell structure) in the second honeycomb carrier 21, the spiral curvature in each spiral cell (typically ECrc) from the inflow end 21a to the outflow end 21b is constant. . This is because it is not necessary to reverse the direction of the flow further toward the rear stage with respect to the exhaust discharged from the outflow end 21b, and therefore, a configuration mainly intended to suppress an increase in pressure loss is selected.

Next, still another aspect of the exhaust gas purification apparatus 1 for an internal combustion engine will be described with reference to FIGS. 14A and 14B.
FIG. 14A is a schematic diagram showing the first honeycomb carrier 11 and the second honeycomb carrier 21 which are the main parts of still another aspect of the exhaust gas purification apparatus for the internal combustion engine shown in FIGS. 3, 4, 6, and 7. In particular, the shape and the action of the inflow end 111a and the outflow end 111b of the first honeycomb carrier 11 are shown.
FIG. 14B is a schematic diagram for contrastingly explaining the operation when the mode as shown in FIG. 14A is not adopted.
14A and 14B, the same reference numerals are given to the corresponding parts in FIGS. 4 and 6 described above.

  As easily understood with reference to FIG. 14A, the outflow end 111b of the first honeycomb carrier 11 has a convex shape that protrudes in the outflow direction of the exhaust gas toward the central axis X side rather than the outer peripheral side. Furthermore, the inflow end 111a of the first honeycomb carrier 11 has a concave shape that is recessed in the inflow direction of exhaust toward the central axis X side rather than the outer peripheral side.

  In the exhaust purification device 1 in FIG. 14A, as described above, the outflow end 111b of the first honeycomb carrier 11 has a convex shape that protrudes in the exhaust outflow direction toward the central axis X side rather than the outer peripheral side. For this reason, it is avoided that the exhaust from the individual cells that are swirled out from the outflow end 111b that is the outflow side end surface through the first honeycomb carrier 11 is dispersed radially and interferes with each other. .

  This operation will be described with reference to FIG. 14B. As shown in FIG. 14B, when the outflow end 11b of the first honeycomb carrier 11 is simply formed in a flat shape, the center of the exhaust discharged as a swirling flow from the outflow end 11b as shown by the arrow The inner swirling flow relatively close to the axis X interferes with the outer swirling flow relatively far from the central axis X. For this reason, the exhaust flow that flows out from the outflow end 11b of the first honeycomb carrier 11 and travels toward the inflow end 21a of the second honeycomb carrier 21 is disturbed, and the efficiency of the direction change and transfer of the exhaust decreases.

  On the other hand, the outflow end 111b of the first honeycomb carrier 11 in FIG. 14A is a convex shape that protrudes in the outflow direction of the exhaust toward the central axis X side rather than the outer peripheral side. The exhaust gas discharged as a swirling flow from is deflected so as to expand toward the outside relatively far from the central axis X. Therefore, it is avoided that the inner swirling flow relatively close to the central axis X interferes with the outer swirling flow. For this reason, the exhaust gas flowing out from the outflow end 111b of the first honeycomb carrier 11 of the first exhaust gas purification unit 10 passes through the exhaust flow direction reversing unit 40 (FIGS. 1 and 2) and is efficiently downstream. Flows into the second honeycomb carrier 21 of the exhaust gas purification unit 20. As a result, the pressure loss of the entire exhaust gas purification device is reduced.

  On the other hand, if the outflow end 111b of the first honeycomb carrier 11 is convex so as to project in the outflow direction of the exhaust toward the central axis X side rather than the outer peripheral side, the flow path of the inner cell relatively close to the central axis X The length is longer than the flow path length of the outer cell relatively far from the central axis X. For this reason, the pressure loss is relatively larger on the inner side than on the outer side of the first honeycomb carrier 11, and the exhaust flow distribution is biased on the inflow end side.

  In view of this phenomenon, in the first honeycomb carrier 11 in FIG. 14A, the inflow end 111a has a concave shape that is recessed in the exhaust inflow direction toward the central axis side rather than the outer peripheral side. Accordingly, there is generally no difference between the channel length of the outer cell relatively far from the central axis X and the channel length of the inner cell relatively closer to the central axis X. For this reason, the distribution of the exhaust flow does not become uneven on the inflow end side. Therefore, the volumetric efficiency of the catalyst does not decrease and the purification performance does not deteriorate.

Next, still another aspect of the exhaust gas purification apparatus 1 for an internal combustion engine shown in FIGS. 1, 2, and 3 will be described with reference to FIGS. 15, 16, 17, and 18.
FIG. 15 schematically shows a partial side cross-section of the exhaust purification device 1, FIG. 16 shows the operation of the exhaust purification device of the internal combustion engine of FIG. 15 (a phenomenon when no other means are taken), and FIG. A partial cross section of the purification device 1 is schematically shown, and FIG. 18 is a partial sectional view of a portion of the exhaust purification device 1 near the outer peripheral surface of the first honeycomb carrier 11.
15, FIG. 16, and FIG. 17 are drawn in the same manner as in FIG. 2 and FIG. 3 corresponding to those described above, and the corresponding parts are given the same reference numerals.

15 and FIG. 16, as in FIG. 2, the left side is the upstream side of the exhaust flow in the exhaust passage 2 (shown by a broken line) of the internal combustion engine, and the right side is the downstream side of the exhaust flow.
A first honeycomb carrier 11 whose outer shape is a substantially cylindrical body is provided in the first exhaust purification section 10, and a catalyst for purifying exhaust gas is carried on the first honeycomb carrier 11.

The exhaust purification device 1 including the first exhaust purification unit 10 and the second exhaust purification unit 20 forms an outermost peripheral surface around the central axis X on the outer peripheral side of the second exhaust purification unit 20, for example, It has an outer shell portion 31 made of a stainless steel plate or the like. In the outer shell portion 31, a carrier partition wall portion 32 that forms a partition wall between the first honeycomb carrier 11 and the second honeycomb carrier 21 is provided.
Further, the inlet side connecting portion 33a whose diameter is narrowed so that the outer shell portion 31 is connected to the internal combustion engine (not shown) side, and the downstream side pipe (not shown) in the exhaust passage 2 for discharging the exhaust flow to the downstream side. An outlet side connecting portion 34 whose diameter is narrowed down so as to be connected to the figure is provided.

  In the exhaust gas purification apparatus 1, untreated exhaust gas 3a (illustrated by a white arrow) from the inlet side connecting portion 33a is the exhaust gas inflow side (inflow end) which is the left end side of the first honeycomb carrier 11 in the drawing. 11a side) and exhaust gas 3b (illustrated by a white arrow) purified by the exhaust gas purification device 1 is discharged from the outlet side connection portion 34.

In the exhaust gas purification apparatus 1 for an internal combustion engine of the embodiment of FIG. 15, when the inlet side connecting portion 33a has a shape with a narrowed diameter as shown in the figure, when no other means are taken. The flow rate of the exhaust gas is biased between the central portion and the peripheral portion of the inflow end 11a of the first honeycomb carrier 11.
FIG. 16 conceptually shows the phenomenon in which the flow rate of the exhaust flow is uneven between the central portion and the peripheral portion of the inflow end 11a of the first honeycomb carrier 11 as described above.
In FIG. 16, an arrow drawn so as to extend from the outside of the inflow end 11 a of the first honeycomb carrier 11 to the inside of the first honeycomb carrier 11 is a concept of exhaust gas flowing into the first honeycomb carrier 11. It expresses. In this case, the distribution density of the arrow lines represents the flow rate of the exhaust flowing into the first honeycomb carrier 11.
As will be understood with reference to FIG. 16, the flow rate of the exhaust gas at the central portion of the inflow end 11 a of the first honeycomb carrier 11 becomes relatively high unless another means is taken. That is, the density deviation is generated such that the flow rate of the exhaust gas in the peripheral portion of the inflow end 11a of the first honeycomb carrier 11 becomes relatively coarse.
For this reason, the volumetric efficiency of the catalyst is lowered, and the purification performance may be deteriorated. Moreover, there is a risk that the pressure loss related to the flow of exhaust gas will increase and the output of the internal combustion engine will decrease.
For this reason, another means as described with reference to FIG. 18 is taken.

As described above, FIG. 18 is a partial cross-sectional view of a portion near the outer peripheral surface of the first honeycomb carrier 11 of the exhaust purification device 1.
When the arrangement of the cells in the first honeycomb carrier 11 in FIG. 18 in a cross-sectional view is considered in comparison with FIG. 11 described above, the difference between them is understood. The arrangement itself in cross-sectional view is the same.
That is, in FIG. 18, the concentric peripheral wall portions are arranged in the order of S81, S82, S83, S84,... From the wall portion directly below the carrier partition wall portion 32 described above toward the inside (center axis X). A predetermined number is arranged as in S8n.

Further, side wall portions D11, D12, D13,..., D21, D22, D23,..., D31, D32, D33,... In the direction intersecting with the concentric peripheral wall portions S81, S82, S83, S84,. ing.
Here, the feature of the embodiment of FIG. 18 is that the cross-sectional area of each cell Q11, Q22, Q33,... Partitioned by the concentric peripheral wall portion and the side wall portion in the direction intersecting this is larger toward the outer peripheral side. It is a different point.

If attention is paid to the three cells Q11, Q22, and Q33 as a representative, the cell Q11 is partitioned by two concentric peripheral wall portions S81 and S82 and two side wall portions D11 and D12. The cell Q22 is partitioned by two concentric peripheral wall portions S82 and S83 and two side wall portions D21 and D22. Further, the cell Q33 is partitioned by two concentric peripheral wall portions S83 and S84 and two side wall portions D31 and D32.
The cross-sectional area of each of these cells is relatively large at Q11 located on the outer periphery, and the cross-sectional areas are sequentially smaller in the order of Q22, Q33,. In other words, for each cell Q11, Q22, Q33,..., The distance between the pair of concentric peripheral wall portions that define each cell and the pair so that the cross-sectional area thereof becomes larger as the cell located on the outer peripheral side. That is, the interval between the side walls is selected.
In FIG. 18, for convenience of explanation, the cross-sectional area magnitude relationship is exaggerated.

As described above, in the first honeycomb carrier 11 of FIG. 18, the cross-sectional area is relatively larger in the cells separated from the central axis X than in the cells close to the central axis X.
In other words, the concentric peripheral wall portions S81, S82, S83, S84, ... S8n and the side wall portions D11, D12, D13, ..., D21, D22, D23, ..., D31, D32, D33, ... are cell cross-sectional areas. However, the cells separated from the central axis X of the honeycomb carrier are arranged so as to be relatively larger than the cells close to the central axis X.
For this reason, the pressure loss relating to the inflow of exhaust gas is smaller in the cell at the position facing the outer peripheral surface of the first honeycomb carrier which is a substantially cylindrical body than in the cell in the vicinity of the central axis X.

Accordingly, even when the diameter of the inlet is narrowed down by the inlet side connecting portion 33a so that the exhaust purification device 1 is smoothly connected to the internal combustion engine, the first exhaust gas from the internal combustion engine faces the small diameter inlet. The honeycomb carrier 11 is moderately dispersed not only on the inner peripheral side but also on the outer peripheral side, so that the flow rate of the exhaust gas at the inflow end 11a is less likely to be uneven.
As a result, the decrease in the effective volume ratio of the catalyst in the first honeycomb carrier 11 is suppressed, and the overall pressure loss is also suppressed.

Next, a method for manufacturing a honeycomb carrier having the spiral cell structure as described above will be described.
One method is a method of obtaining a ceramic honeycomb such as cordierite or titanium alumina or a metal honeycomb such as stainless steel by extruding a clay-like raw material, cutting it with an appropriate size, and performing a sintering process. In this case, at the time of extrusion molding, a die for injecting the clay-like raw material is rotated to obtain a honeycomb carrier having a spiral flow path.

Another method is a method using a 3D printer. That is, a concave strip having an inclined angle is formed on a plate-like body by a 3D printer, and such a plate-like body is wound to obtain a honeycomb carrier having a spiral flow path. When a stainless steel metal foil or ceramic sheet is wound and then formed into a honeycomb shape, it is usually corrugated at right angles to the winding direction. A flow path is formed.
For supporting the catalyst on the honeycomb carrier having a spiral cell structure, it is possible to apply a known method for sucking slurry or flowing compressed air.

As mentioned above, although the several aspect in embodiment of the exhaust gas purification apparatus of this invention was demonstrated, this invention is not limited as long as it mentioned above, Furthermore, it can implement by carrying out various deformation | transformation changes.
For example, in the above-described embodiment, the carrier partition wall portion 32 is provided between the first honeycomb carrier 11 and the second honeycomb carrier 21. However, the carrier partition wall portion 32 is omitted. It is also possible. That is, once the exhaust gas flows into the first honeycomb carrier 11 (the plurality of first stage cells) from the inflow end 11a, it can be easily moved to the outer peripheral side without providing a separate partition wall around the first honeycomb carrier 11. Since it does not leak out, there is no major problem even if the carrier partition wall 32 is omitted.
In the above-described embodiment, the cells (a plurality of second stage cells) of the second honeycomb carrier 21 have a spiral cell structure. However, the second stage cells of the second honeycomb carrier 21 have a spiral cell structure. It is also possible to use a mode that does not turn. In this case, manufacture is easy and it is excellent in terms of cost.
Therefore, the exhaust purification device of various aspects as described above is also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Exhaust purification apparatus 10 ... 1st exhaust purification part 11 ... 1st honeycomb carrier 20 ... 2nd exhaust purification part 21 ... 2nd honeycomb support 40 ... Exhaust flow direction inversion part

Claims (9)

A first exhaust gas purification unit provided in an exhaust passage of the internal combustion engine and carrying a catalyst for purifying exhaust gas on the first honeycomb carrier;
A second exhaust gas purification unit provided outside the first exhaust gas purification unit, wherein a catalyst for purifying exhaust gas is supported on the second honeycomb carrier;
An exhaust flow direction reversing unit that reverses the direction of the exhaust flow that flows out of the first exhaust purification unit and guides it to the second exhaust purification unit,
The exhaust purification device for an internal combustion engine, wherein the first honeycomb carrier has a first spiral cell structure in which a plurality of first stage cells extend so as to draw a spiral from the exhaust inflow side to the outflow side.   2. The internal combustion engine according to claim 1, wherein the first honeycomb carrier has a substantially cylindrical outer shape, and the plurality of first-stage cells have a smaller curvature of the spiral on the exhaust inflow side than on the outflow side. Engine exhaust purification system.   The outer shape of the second honeycomb carrier is substantially a hollow cylindrical body, and a plurality of second-stage cells are formed of spiral hollow bodies having a revolving direction reversed from the spiral in the first-stage cells. The exhaust emission control device for an internal combustion engine according to claim 1 or 2, wherein the exhaust gas purification device has a second spiral cell structure extending in the axial direction.   The outer shape of the first honeycomb carrier is substantially cylindrical, and the plurality of first-stage cells draw a spiral having a larger curvature toward the cell on the center side of the first honeycomb carrier than on the outer peripheral side. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 3, configured as described above.   5. The internal combustion engine according to claim 1, wherein the first honeycomb carrier has a convex shape in which the shape of the end face on the exhaust outlet side protrudes in the exhaust outlet direction toward the center rather than the outer peripheral side. Exhaust purification equipment.   The exhaust purification device for an internal combustion engine according to claim 5, wherein the first honeycomb carrier has a concave shape in which the shape of the end face on the exhaust inflow side is recessed in the inflow direction of exhaust toward the center side rather than the outer peripheral side.   In the first honeycomb carrier, the cell wall defining the first stage cell has a concentric peripheral wall portion and a radial side wall portion in a cross-sectional view orthogonal to the central axis. An exhaust emission control device for an internal combustion engine according to claim 1. The first honeycomb carrier has a peripheral wall portion concentrically in a cross-sectional view perpendicular to the central axis, and a side wall portion in a direction intersecting the peripheral wall portion, in which the cell wall defining the first stage cell is perpendicular to the central axis.
The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 2 to 6, wherein the peripheral wall portion and the side wall portion are arranged so that cross-sectional areas of the first stage cells are equal to each other. The first honeycomb carrier has a peripheral wall portion concentrically in a cross-sectional view perpendicular to the central axis, and a side wall portion in a direction intersecting the peripheral wall portion, in which the cell wall defining the first stage cell is perpendicular to the central axis.
The exhaust of the internal combustion engine according to any one of claims 2 to 6, wherein the peripheral wall portion and the side wall portion are arranged such that a cross-sectional area of the first stage cell is larger toward an outer peripheral side than a central axis side. Purification equipment.

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