JP3376856B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust emission control device for an internal combustion engine.

[0002]

2. Description of the Related Art Exhaust gas of an internal combustion engine, especially a diesel engine, contains harmful particulates containing carbon as a main component, and such particulates are discharged before the exhaust gas is released to the atmosphere. It is required to be removed. Therefore, a particulate trap is arranged in the exhaust system of the diesel engine. Since such a particulate trap has a large exhaust resistance as the amount of collected particulates increases, it is necessary to burn the collected particulates and regenerate the particulate trap itself.

To regenerate such a particulate trap, the heat of the exhaust gas at a high temperature during high-load operation of the engine at high speed is generally used, and the particulate trap is regenerated every operation. However, there is no guarantee that the engine high-load and high-speed operation will be performed frequently, and a large amount of particulates may be trapped in the particulate trap during regeneration. The combustion of particulates propagates from the exhaust gas upstream side of the particulate trap to the downstream side, and the combustion heat is concentrated on the exhaust gas downstream portion of the particulate trap. Therefore, if the amount of collected particulates during regeneration is above a certain level, the overall combustion heat of particulates becomes large, and there is a possibility of melting damage in the exhaust gas downstream portion of the particulate trap where the combustion heat of particulates concentrates. There is.

Japanese Patent Application Laid-Open No. 60-65219 proposes to divide a particulate trap into two along the longitudinal axis to form a gap. This particulate trap has a certain amount of particulates trapped in the particulate trap, and when the flow path resistance of the particulate trap greatly increases, after that, the exhaust gas mainly passes through the gap, and in the particulate trap, Since the particulates are hardly collected, the amount of particulate collection is said to be limited.

[0005]

The particulate trap generally has a structure composed of a large number of trap passages having at least one side wall having a trap wall extending in the longitudinal direction, thereby collecting the particulates. The total area of the trap wall is increased. In such a particulate trap, the flow passage resistance of each trap passage is inevitably relatively high, but a large number of trap passages allow a large amount of exhaust gas to pass through.

In the above-mentioned prior art, the flow path resistance of the gap should be made extremely small in order to allow a large amount of exhaust gas to pass after a certain amount of particulates are trapped in the particulate trap. As a result, even when no particulate matter is collected, the exhaust gas is more likely to pass through the gaps than the trap passages of the particulate trap, and the particulate matter collection rate before a certain amount of particulate matter is collected. Is very low.

Therefore, an object of the present invention is to maintain a high particulate collection rate before particulate collection to some extent and to limit the particulate collection amount to some extent. Is to provide.

[0008]

According to a first aspect of the present invention, there is provided an exhaust gas purification apparatus for an internal combustion engine, which has a plurality of trap passages and is capable of passing a large amount of exhaust gas. And a communication means having a communication passage capable of passing a large amount of exhaust gas, wherein each of the trap passages of the particulate trap means has a trap wall extending in the longitudinal direction as at least one side wall, It is intended to pass the trap wall to the gas, the a particulate trap means and said communication means are arranged in parallel with each other exhaust system, the Patikyu
The rate trap means is the center of the particulate trap
And the communication means is provided in the section.
It is provided at the periphery of the wrap, and
The air upstream side opening area is
The flow passage resistance of each of the communication passages is greater than the flow passage resistance of each of the trap passages by being smaller than the air upstream side opening area .

[0009]

The exhaust gas purifying apparatus for an internal combustion engine according to the second aspect of the present invention has a plurality of trap passages and a large amount of exhaust gas.
Particulate trap means capable of passing gas and gas,
Communication that has multiple communication passages and can pass a large amount of exhaust gas
Means for providing the particulate trap means
Each of the trap passages has a trap wall extending in the longitudinal direction.
Has at least one side wall, and
The particulates that pass through the wall.
The wrap means and the communication means are arranged in parallel with each other in the engine exhaust system.
Are arranged in columns, each of the longitudinal length of the communication passage, by which the long grass from each longitudinal length of said trap passage, the flow paths of the communication path
The resistance is greater than the flow path resistance of each of the trap passages.
Characterized by a threshold .

An exhaust gas purification apparatus for an internal combustion engine according to a third aspect of the present invention has a plurality of trap passages and a large amount of exhaust gas.
Particulate trap means capable of passing gas and gas,
Communication that has multiple communication passages and can pass a large amount of exhaust gas
Means for providing the particulate trap means
Each of the trap passages has a trap wall extending in the longitudinal direction.
Has at least one side wall, and
The particulates that pass through the wall.
The wrap means and the communication means are arranged in parallel with each other in the engine exhaust system.
The flow path resistance of each of the communication passages arranged in rows
Is greater than the flow resistance of each of the trap passages.
At least one of the trap passages is composed of only one portion on the exhaust upstream side and the exhaust downstream side of the trap wall, and the at least one communication passage is disposed adjacent to the trap wall of the at least one trap passage. The at least one communicating passage has at least one trap wall of the at least one trap passage.

An exhaust gas purifying apparatus for an internal combustion engine according to a fourth aspect of the present invention has a plurality of trap passages and a large amount of exhaust gas.
Particulate trap means capable of passing gas and gas,
Communication that has multiple communication passages and can pass a large amount of exhaust gas
Means for providing the particulate trap means
Each of the trap passages has a trap wall extending in the longitudinal direction.
Has at least one side wall, and
The particulates that pass through the wall.
The wrap means and the communication means are arranged in parallel with each other in the engine exhaust system.
The partition walls that are arranged in rows and between the exhaust upstream side openings of two adjacent communication passages are thickened to make it difficult for exhaust gas to collide with the partition walls and flow into the adjacent communication passages .
Therefore, the flow path resistance of each of the communication passages is
It is characterized in that it is larger than the flow resistance of each of the lap passages .

According to a fifth aspect of the present invention, there is provided an exhaust gas purifying apparatus for an internal combustion engine, which has a plurality of trap passages and a large amount of exhaust gas.
Particulate trap means capable of passing gas and gas,
Communication that has multiple communication passages and can pass a large amount of exhaust gas
Means for providing the particulate trap means
Each of the trap passages has a trap wall extending in the longitudinal direction.
Has at least one side wall, and
The particulates that pass through the wall.
The wrap means and the communication means are arranged in parallel with each other in the engine exhaust system.
The exhaust upstream side end surfaces of the communication passages are arranged in rows, and the exhaust upstream side end surfaces of the trap passages are located on the exhaust upstream side of the exhaust upstream side end surfaces of the trap passages.
The flow path resistance of each of the paths is equal to that of the trap path.
It is characterized in that it is larger than the flow path resistance .

According to a sixth aspect of the present invention, there is provided an exhaust gas purifying apparatus for an internal combustion engine, which has a plurality of trap passages and a large amount of exhaust gas.
Particulate trap means capable of passing gas and gas,
Communication that has multiple communication passages and can pass a large amount of exhaust gas
Means for providing the particulate trap means
Each of the trap passages has a trap wall extending in the longitudinal direction.
Has at least one side wall, and
The particulates that pass through the wall.
The wrap means and the communication means are arranged in parallel with each other in the engine exhaust system.
The exhaust gas upstream openings of the two adjacent trap passages arranged in a row have a tapered projection shape that projects toward the exhaust upstream side, and exhaust gas is directed to the adjacent trap passages by the tapered projection shape. to facilitate the inflow
The flow path resistance of each of the communication passages is determined by the trap
It is characterized in that it is larger than the flow resistance of each of the passages .

[0015]

1 is a cross-sectional view showing a first embodiment of an exhaust purification system for an internal combustion engine according to the present invention. In the figure, 1 is an engine exhaust passage, and 2 is a particulate trap. Particulate trap 2
For example, as shown in FIG. 2 and FIG. 3 which is a partially enlarged view of the AA cross section of FIG. 2, it is a porous substance particulate trap made of a porous substance such as ceramics. This particulate trap has a plurality of axial space subdivided by a plurality of partition walls 21 extending in the longitudinal direction,
In two adjacent axial spaces, one is closed on the exhaust upstream side and the other is closed on the exhaust downstream side by a blocking member 22 made of ceramic or the like. In this way, the two adjacent spaces in the axial direction allow the exhaust gas flowing from the exhaust upstream side to pass through the partition wall 2.
The partition wall 21 made of a porous material serves as a trap wall to flow out to the downstream side of the exhaust gas through the exhaust gas 1 and serves as a trap wall to collect particulates when passing the exhaust gas.

The particulate trap 2 is composed of a non-woven fabric of heat-resistant metal fibers and a corrugated plate of heat-resistant metal, as shown in FIG. 4 and FIG. It may be used as a metal fiber particulate trap. In this particulate trap, two non-woven fabrics 24a and 24b and two corrugated plates 25a and 25b are laminated in a thickness direction differently from each other and spirally wound.
The nonwoven fabric and the corrugated plate form a plurality of axial spaces. Examples of the heat-resistant metal fiber forming the non-woven fabric and the heat-resistant metal forming the corrugated sheet include Fe-Cr
-Al alloy or Ni-Cr-Al alloy can be used. The two nonwoven fabrics 24a and 24b are continuously welded in a spiral shape with one surface of each of them being in close contact with each other at the exhaust upstream end, and the other surface of each being in close contact with each other at the exhaust downstream end. It is continuously spirally welded.
Thus, the two axially adjacent axial spaces are
The exhaust gas flowing from the exhaust gas upstream side becomes the trap passage 20 through which one of the non-woven fabrics flows out to the exhaust gas downstream side,
The non-woven fabric serves as a trap wall and collects particulates when passing through the exhaust gas. These two particulate traps allow a large amount of exhaust gas to pass by the plurality of trap passages 20 formed.

In FIG. 1, reference numeral 3 is a communication pipe which connects the exhaust gas upstream side and the exhaust gas downstream side of the particulate trap 2 in the engine exhaust passage 1. In the communication tube 3, a large number of thin tubes 3a are arranged in close contact with each other. In the present embodiment, two such communication pipes 3 are arranged, and a large amount of exhaust gas can pass even if it bypasses the particulate trap 2.

The flow path resistance in each trap passage 20 of the particulate trap 2 is the inflow resistance component when the exhaust gas flows into the exhaust upstream side opening and the trap passage 20.
It has a flow resistance component when the exhaust gas flows through the inside and a passage resistance component when the exhaust gas passes through the trap wall. On the other hand, the flow path resistance in each thin tube 3a arranged in the communication tube 3 is the inflow resistance component when the exhaust gas flows into the exhaust upstream side opening because the thin tube 3a does not have a trap wall, It has a flow resistance component when the exhaust gas flows in the thin tube 3a. In general, the smaller the upstream opening area, the larger the inflow resistance component, and the flow path resistance increases. In addition, the flow resistance component increases as the flow path cross-sectional area is small and the flow path length is long, and the flow path resistance is increased.

In the present embodiment, since the exhaust upstream side opening area and the flow passage cross-sectional area of the thin tubes 3a are made extremely small as compared with the trap passage 20, the passage resistance of each thin tube 3a is the passage resistance. Even if it does not have a component, it is larger than the flow passage resistance of the trap passage 20. The length of the thin tube 3a is longer than that of the trap passage 20.
Is a factor that makes the flow path resistance of 1 larger than the flow path resistance of the trap passage 20.

In the exhaust gas purifying apparatus of this embodiment having such a configuration, the exhaust gas initially flows only through the trap passages 20 having relatively small flow passage resistance, and the trap walls satisfactorily trap particulates. Gathered. In this way, the particulates continue to be collected, and when the engine high-load high-speed operation is performed, the particulate trap 2 is regenerated by being burned by the heat of the exhaust gas of high temperature. If such an engine high-load and high-speed operation is not performed for a while, the amount of particulate trapped in the particulate trap 2 increases, so the flow passage resistance of each trap passage 20 is considerably large compared to the beginning. Finally, the flow path resistance of each thin tube 3a in the communication tube 3 is slightly larger than the flow path resistance.

The two communication pipes 3 allow a large amount of exhaust gas to pass therethrough, as described above. Therefore, after the flow passage resistance of each trap passage 20 becomes larger than the flow passage resistance of the thin pipe 3a, the exhaust gas flows only through each thin pipe 3a in the communication pipe 3 having a relatively small flow passage resistance. As a result, no more particulates will be trapped in the particulate trap 2 and the particulate trapping amount can be limited to some extent. At this time, if the engine high-load and high-speed operation is performed, the exhaust gas does not pass through the particulate trap 2, but the exhaust gas comes into contact with the exhaust upstream side end surface of the particulate trap 2 to transfer heat, so It is possible to sufficiently start the burning of the curate. During the combustion of the particulates, the particulate trap 2 collects only a limited amount of particulates.
The problem of melting loss in the exhaust gas downstream portion of the particulate trap 2 does not occur. Thus, when the regeneration of the particulate trap 2 is completed, each trap passage 2
Since the channel resistance of 0 becomes smaller than the channel resistance of each thin tube 3a again, the exhaust gas flows only through each trap passage 20 and the collection of particulates is restarted.

FIG. 6 is a sectional view showing a second embodiment of the exhaust emission control system for an internal combustion engine according to the present invention. In the figure, 1 is an engine exhaust passage, and 4 is a particulate trap. In this embodiment, the communication pipe 3 as in the first embodiment is not provided. The particulate trap 4 is, for example, a porous particulate trap shown in FIG. 7 and FIG. 8 which is a partially enlarged sectional view taken along the line CC of FIG. 7. The difference between this particulate trap and the porous substance particulate trap shown in FIG. 2 will be described below.

As in the porous particulate trap of FIG. 2, the particulate trap has a trap passage 40 formed by two adjacent axial spaces in the central portion. However, in the peripheral portion, the cross-sectional area of the axial space is smaller than that in the central portion, and the communication path 50 is formed without blocking the exhaust upstream side and the exhaust downstream side. In this way, in this particulate trap, the central portion becomes the particulate trap means region p corresponding to the particulate trap 2 of the first embodiment, and the peripheral portion thereof the communicating means region corresponding to the communicating pipe 3 of the first embodiment. It becomes q. The particulate trap means and the communication means enable a large amount of exhaust gas to pass through the plurality of trap passages 40 and the plurality of communication passages 50, respectively.
The exhaust upstream side opening area and the flow passage cross-sectional area of each communication passage 50 are
The flow path resistance of each communication passage 50 is very small compared to each trap passage 40, and therefore
The flow path resistance is greater than 0.

If such a particulate trap is arranged in the engine exhaust passage 1, the exhaust gas initially flows only through each trap passage 40 having a relatively small passage resistance, as in the first embodiment. Good trapping of particulates in the particulate trap means is realized. As the amount of collected particulates increases, the flow passage resistance of each trap passage 40 increases and becomes slightly larger than the flow passage resistance of each communication passage 50. After this, the exhaust gas flows only through the respective communication passages 50 having relatively small flow path resistance, and the amount of particulate collection in the particulate trap means can be limited to some extent. In the particulate trap regeneration at this time, the exhaust gas at the time of engine high load high speed operation flows through the communication means, but since the communication means are arranged in parallel around the particulate trap means, the high temperature The heat of the exhaust gas is sufficiently transmitted from the communication means to the particulate trap means, and the particulate trap means can satisfactorily burn the particulates.

The particulate trap 4 of the exhaust gas purifying apparatus of this embodiment may be a metal fiber particulate trap as shown in FIG. 9 and an enlarged view of a portion indicated by an arrow D in FIG. The difference between this particulate trap and the metal fiber particulate trap shown in FIG. 4 will be described below. In the particulate trap, the trap passage 40 is formed by two axially adjacent spaces in the radial direction in the central portion, similarly to the metal fiber particulate trap of FIG. However, in the peripheral portion, the wave height and the wave width of the corrugated sheet are reduced to reduce the cross-sectional area of the axial space, and the communication paths 50 are formed without welding the nonwoven fabrics on the exhaust upstream side and the exhaust downstream side. Has been formed. Thus, also in this particulate trap, the central portion becomes the particulate trap means region p and the peripheral portion becomes the communication means region q. Thus, the particulate trap means and the communicating means allow a large amount of exhaust gas to pass through the plurality of trap passages 40 and the plurality of communicating passages 50, and the passage resistance of each communicating passage 50 is equal to each trap passage. It is made larger than the flow path resistance of 40. Even if such a particulate trap is arranged in the engine exhaust passage 1, the same effect as described above can be obtained.

Further, the particulate trap 4 of the exhaust purification system of this embodiment may be a particulate trap as shown in FIG. This particulate trap is a porous material or a metal fiber particulate trap having a particulate trap means region p and a communicating means region q as shown in FIG. 7 or FIG.
A trap passage is formed in the central particulate trap means region p, and a communication passage is formed in the surrounding communication means region q. Particulate trap means area p
Is L1, whereas the communication means region q projects toward the exhaust gas downstream side, and the length of the communication means region q is L2, which is longer than L1. Therefore, in the communication passage of the communication means, the flow resistance component is increased as compared with the particulate trap shown in FIG. 7 or 9, and the flow passage resistance is increased.

The flow passage resistance of the trap passage in the particulate trap means cannot be reduced so much because the passage resistance component in the trap wall becomes dominant even if the flow passage cross-sectional area is increased. On the other hand, the flow path resistance of the communication passage in the communication means cannot be freely increased only by this because there is a manufacturing limit even if the exhaust upstream side opening area and the flow path cross-sectional area are reduced. However,
By thus increasing the length of the communication passage, it is possible to freely increase the flow passage resistance of the communication passage. As a result, it is possible to freely increase the flow path resistance difference between the flow path resistance and the trap passage where the flow path resistance cannot be made too small, and when the particulate trap means has excellent heat resistance and melting loss is unlikely to occur, limit the amount of particulate collection. Can be relatively large. This reduces the chance that the particulate collection amount is limited, that is, the chance that the exhaust gas passes through the communication passage, and reduces the particulate emission into the atmosphere.

Further, the particulate trap 4 of the exhaust gas purification apparatus of this embodiment may be a particulate trap as shown in FIG. This particulate trap is a porous material or a metal fiber particulate trap having a particulate trap means region p and a communicating means region q as shown in FIG. 7 or FIG.
A trap passage is formed in the central particulate trap means region p, and a communication passage is formed in the surrounding communication means region q. The communication passage of the communication means region q is formed so as to protrude toward the exhaust upstream side as it is spaced apart from the particulate trap means region p. As a result, the length of the communication passage is increased to increase the flow passage resistance, and the flow passage resistance of the exhaust upstream direction space facing the particulate trap means region p is extremely high at the exhaust upstream opening position of the communication passage. Since it is very small, the exhaust gas easily flows in this space as shown by the arrow, that is, it becomes difficult to flow into the communication passage. In this way, the flow path resistance difference from the trap passage can be freely expanded, and the amount of particulate trapped in the particulate trap means can be increased.

Further, the particulate trap 4 of the exhaust purification system of the present embodiment may be a particulate trap as shown in FIG. 14 which is a view taken in the direction of arrow E of FIG. 13 and FIG. FIG. 13 is an enlarged cross-sectional view of the vicinity of the boundary between the particulate trap means region p and the communication means region q of the porous substance particulate trap as shown in FIG. In this particulate trap, a blocking member 22 'for forming the trap passage 40 has a quadrangular pyramid shape and projects toward the exhaust gas upstream side. In the past, the exhaust gas collided with the flat surface on the exhaust upstream side of the occluding member and became a turbulent flow, and it was difficult to flow into the exhaust upstream side opening of the trap passage. With the quadrangular pyramid shape, such a turbulent flow is less likely to be formed and smoothly flows into the trap passage 40, that is, the inflow resistance component of the trap passage 40 is reduced and the flow passage resistance can be reduced. . Thereby, the flow path resistance difference between the trap passage 40 and the communication passage 50 'can be increased.

Further, since the partition wall 21 'forming the communication passage 50' in the communication means region q is thicker than the partition wall 21 'forming the trap passage 40 in the particulate trap means region p, the communication passage is formed. The exhaust upstream side opening area and the flow passage cross-sectional area of 50 'are made smaller than those of the particulate trap shown in FIG.
As the flow resistance of 0'becomes large, the exhaust gas collides with the thick partition wall and becomes a turbulent flow, which makes it difficult for the exhaust gas to flow into the communication passage 50 '. The road resistance can be further increased. Thus
The flow path resistance difference between the trap passage 40 and the communication passage 50 ′ can be further expanded.

If the shape of the occluding member is a cone or a pyramid, it is possible to suppress the generation of turbulent flow at the time of collision. In the case of this particulate trap, the exhaust gas upstream side openings of the trap passage 40 are formed in four directions around the occluding member 22 ', so that the exhaust gas can be satisfactorily guided to the exhaust gas upstream side openings of the trap passages. A quadrangular pyramid shape having a surface that matches each direction is selected as the occluding material shape.
Based on this idea, the shape of the occluding material is preferably selected from a plurality of pyramid shapes depending on the arrangement of the trap passages.

Further, the particulate trap 4 of the exhaust purification system of this embodiment may be a particulate trap as shown in FIG. FIG. 15 shows a trap passage 40 in the particulate trap means region p in the metal fiber particulate trap as shown in FIG.
When joining the metal fiber non-woven fabrics to form
The bent portion of the non-woven fabric is elongated so as to project to the upstream side of the exhaust gas to have a smooth tapered cross-sectional shape. As a result, the exhaust gas easily flows into the trap passage 40, as in the case of the quadrangular pyramid-shaped blocking member described above. Further, in the exhaust gas upstream side portion of the communication means region q, the spiral blocking member 51 is arranged between the surfaces of the two nonwoven fabrics bonded to each other in the particulate trap means region p. As a result, the exhaust gas collides with the plug 51 and becomes a turbulent flow, which makes it difficult for the exhaust gas to flow into the communication passage 50. In this way, FIG.
Similar to the particulate trap shown in (1), the flow passage resistance difference between the trap passage 40 and the communication passage 50 can be increased.

Further, the particulate trap 4 of the exhaust gas purification apparatus of this embodiment may be a particulate trap as shown in FIG. 16 and a view taken in the direction of arrow F of FIG. FIG. 16 is an enlarged partial cross-sectional view of a porous substance particulate trap. In the particulate trap, a plurality of axial spaces are subdivided by partition walls 28 made of a porous material, and these axial spaces are further subdivided by partition walls 28 '. The blocking member 22 is provided on the exhaust gas downstream side of the axial space which is not further subdivided. In this way, the axial space closed by the blocking member 22 becomes the trap passage 60, and the further subdivided axial space is provided with the communication passage 70 arranged adjacent to the trap wall of the trap passage 60.
Becomes

The trap passage 60, unlike the conventional trap passage having the exhaust upstream side portion and the exhaust downstream side portion of the trap wall, has only the exhaust upstream side portion with respect to the trap wall (partition wall 28). After passing through the trap wall, the exhaust gas flows out from the communication passage 70 to the exhaust downstream side. Therefore, the trap passage 60 and the communication passage 70
It can be considered that the flow resistance components of the trap passage 60 are substantially equal to each other. In order to make the flow passage resistance of the trap passage 60 smaller than the flow passage resistance of the communication passage 70,
It is necessary to make it smaller than the inflow resistance component of the communication passage 70 more than the passage resistance component of the trap wall, but this can be realized by making the exhaust upstream side opening area different as shown in the figure. The particulate trap having the particulate trap means and the communicating means is relatively large because each means is configured to pass a large amount of exhaust gas, but in this way, a part of the trap passage 60 ( In this case, the downstream side of the trap wall)
By using as a communication passage, it is possible to prevent the particulate trap from increasing in size.

Further, the particulate trap 4 of the exhaust purification system of the present embodiment may be a particulate trap as shown in FIG. 18 and a sectional view taken along line GG of FIG. FIG. 18 is a partially enlarged cross-sectional view of the porous substance particulate trap. Similar to the particulate trap shown in FIG. 16, this particulate trap has an axial direction space which is subdivided and further subdivided by the partition walls 28 and 28 ′, and the axial line which is not subdivided by the occluding material 22. The exhaust gas upstream side of the directional space is closed. Thus, the occluding material 2
The axial space closed by 2 is the trap passage 6
0 ', and the further subdivided axial space is the communication passage 7 disposed adjacent to the trap wall of the trap passage 60'.
It becomes 0 '.

Unlike the conventional trap passage having the exhaust upstream side portion and the exhaust downstream side portion of the trap wall, the trap passage 60 'has only the exhaust downstream side portion from the trap wall (partition wall 28). Instead, the exhaust gas flows in through the communication passage 70 ′, passes through the trap wall, and then flows out through the trap passage 60 ′ toward the exhaust downstream side. Therefore, in order to make the flow passage resistance of the trap passage 60 'smaller than the flow passage resistance of the communication passage 70', the trap passage 60 '
The flow resistance component of the
It is necessary to make it smaller than the flow resistance component of the communication passage 70 ', but this can be realized by making the flow passage cross-sectional areas different as shown in the drawing. In this way, by utilizing a part of the trap passage 60 '(in this case, a portion upstream of the trap wall) as a communication passage, it is possible to prevent the particulate trap from increasing in size.

Further, the particulate trap 4 of the exhaust purification system of the present embodiment may be a particulate trap as shown in FIG. 21 which is a view taken in the direction of arrow H of FIG. 20 and FIG. FIG. 20 is an enlarged partial cross-sectional view of the metal fiber particulate trap. This particulate trap is one of the two corrugated plates wound in a spiral shape,
One having a small wave height and a small wave width is used, and only the surfaces of the two nonwoven fabrics that come into contact with the other corrugated plate are joined on the exhaust downstream side. Thus, the axial space formed by the normal corrugated plate becomes the trap passage 60, and the axial space formed by the small corrugated plate becomes the communication passage 70 disposed adjacent to the trap wall (metal fiber nonwoven fabric) of the trap passage 60.

The trap passage 60 has only a portion on the exhaust upstream side of the trap wall, and the exhaust gas flows out from the communication passage 70 to the exhaust downstream side after passing through the trap wall. Therefore, the trap passage 60 and the communication passage 7
It can be considered that the flow resistance components at 0 are almost equal, and in order to make the flow passage resistance of the trap passage 60 smaller than the flow passage resistance of the communication passage 70, the inflow resistance component of the trap passage 60 is made to be the passage resistance component of the trap wall. As described above, it is necessary to make it smaller than the inflow resistance component of the communication passage 70, but as shown in the figure, this can be realized by making the exhaust upstream side opening area different depending on the wave height and wave width of the two corrugated plates. It is possible. In this way, by using a part of the trap passage 60 (in this case, a portion on the downstream side of the trap wall) as a communication passage, it is possible to prevent the particulate trap from increasing in size.

Further, the particulate trap 4 of the exhaust gas purification apparatus of this embodiment may be a particulate trap as shown in FIG. 22 and FIG. 23 which is a view taken in the direction of arrow I in FIG. FIG. 22 is an enlarged partial cross-sectional view of the metal fiber particulate trap. Similar to the particulate trap shown in FIG. 20, this particulate trap uses one having a small wave height and a small wave width as one of the two corrugated sheets wound in a spiral shape, and the other corrugated sheet in the two nonwoven fabrics. Only the surfaces contacting with each other are joined on the upstream side of the exhaust gas. Thus, the axial space formed by the normal corrugated plate becomes the trap passage 60 ', and the axial space formed by the small corrugated plate becomes the communication passage 70' arranged adjacent to the trap wall (metal fiber nonwoven fabric) of the trap passage 60 '.

The trap passage 60 'has only a portion on the exhaust downstream side of the trap wall. Exhaust gas flows in from the communication passage 70', passes through the trap wall, and then passes through the trap passage 60 'to reach the exhaust downstream. It flows out to the side.
Therefore, the flow passage resistance of the trap passage 60 'is set to the communication passage 70'.
In order to make it smaller than the flow path resistance of
It is necessary that the flow resistance component of 0'be smaller than the flow resistance component of the trap wall, and smaller than the flow resistance component of the communication passage 70 '. This can be achieved by giving different road cross-sectional areas. In this way, by utilizing a part of the trap passage 60 '(in this case, a portion upstream of the trap wall) as a communication passage, it is possible to prevent the particulate trap from increasing in size.

The particulate trap shown in FIGS. 7, 9, 11, 12, 13, and 15 has a particulate trap means region p in the center and a communication means region q in the periphery. . This is because the exhaust gas flow generally has a higher flow velocity in the central portion, so that the exhaust gas easily flows into the trap passage more than the flow passage resistance difference between the communication passage and the trap passage. However, if the flow path resistance difference between the communication passage and the trap passage is made sufficiently large, of course, the reverse configuration is possible, and further, the communication means can be provided in any part of the particulate trap. As the particulate trap used in the second embodiment, various features have been described with reference to the drawings, but these features can be arbitrarily combined to form a particulate trap.

[0042]

According to the exhaust gas purifying apparatus for an internal combustion engine according to the first aspect of the present invention, there is provided a plurality of particulate trap means capable of passing a large amount of exhaust gas and a plurality of communicating passages. the are arranged in parallel with each other and communication means capable of passing a large amount of exhaust gas has, Patti
The particulate trap means of the particulate trap
It is provided in the center and the communication means is a particulate trap.
Provided on the periphery of the exhaust pipe and upstream of each exhaust
The opening area is the exhaust upstream opening of each trap passage.
By making the area smaller than the area, the flow passage resistances of the communicating passages are larger than the flow passage resistances of the trap passages, so the exhaust gas initially has a relatively small passage resistance central portion of the particulate trap. The particulates can be satisfactorily collected by passing through the trap passage. When the amount of particulate collection increases and reaches a certain level, the flow passage resistance of the trap passage increases and becomes larger than the flow passage resistance of the communication passage.
Peripheral trap circumference with relatively small flow resistance
As a result of passing through the communication passage of the surrounding portion, the amount of particulate collection can be limited.

[0043]

According to the exhaust gas purifying apparatus for an internal combustion engine according to the second aspect of the present invention, since the longitudinal length of each of the communicating passages is longer than the longitudinal length of each of the trap passages, the trap passage can be easily formed. It is possible to obtain the above-described effect by making the flow path resistance of the above-mentioned smaller than the flow path resistance of the communication path.

According to the exhaust gas purifying apparatus for an internal combustion engine according to the third aspect of the present invention , the flow path resistance of each of the communication passages is increased.
Is larger than the flow path resistance of each trap passage
In addition, the above-mentioned effect can be obtained, and at least one trap passage is composed of only one portion on the exhaust upstream side and the exhaust downstream side of the trap wall, and at least one trap passage has at least one trap passage. Since one communication passage is arranged adjacently and at least one communication passage has the trap wall of at least one trap passage as at least one side wall, the other portion on the exhaust upstream side and the exhaust downstream side of the trap passage is formed. Is shared with the communication passage, and the exhaust emission control device can be downsized.

According to the exhaust gas purifying apparatus for an internal combustion engine of the present invention as defined in claim 4 , the partition wall between the exhaust gas upstream side openings of the two adjacent communication passages is made thick, and the exhaust gas collides with this partition wall. Since it is difficult to flow into the adjacent communication passage, the flow passage resistance of the trap passage can be easily made smaller than the flow passage resistance of the communication passage to obtain the above-mentioned effect.

According to the exhaust gas purifying apparatus for an internal combustion engine of the present invention as defined in claim 5 , the exhaust upstream side end faces of the communication passages are located on the exhaust upstream side of the exhaust upstream side end faces of the trap passages. to have the exhaust gas is less likely to flow into the communication passage, can be easily passage resistance of the trap passages smaller than the flow path resistance of the communication path, the effect of the above
Obtainable.

According to the exhaust gas purifying apparatus for an internal combustion engine according to the sixth aspect of the present invention, a space between the two adjacent trap passages on the exhaust upstream side is formed into a tapered projecting shape projecting to the exhaust upstream side. Since the exhaust gas is made to easily flow into the adjacent trap passage due to the tapered projection shape, the flow passage resistance of the trap passage can be easily made smaller than the flow passage resistance of the communication passage , and the above-mentioned effect can be obtained. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an exhaust emission control device for an internal combustion engine according to the present invention.

FIG. 2 is a longitudinal sectional view of a particulate trap used in the exhaust gas purification device of FIG.

FIG. 3 is an enlarged partial sectional view taken along the line AA of FIG.

FIG. 4 is a longitudinal sectional view of another particulate trap used in the exhaust emission control device of FIG.

5 is an enlarged view of FIG. 4 as viewed in the direction of arrow B. FIG.

FIG. 6 is a cross-sectional view showing a second embodiment of an exhaust purification system for an internal combustion engine according to the present invention.

7 is a longitudinal cross-sectional view of a particulate trap used in the exhaust emission control device of FIG.

8 is an enlarged partial cross-sectional view taken along line CC of FIG.

9 is a longitudinal sectional view of another particulate trap used in the exhaust emission control device of FIG.

FIG. 10 is an enlarged view taken along the arrow D in FIG.

FIG. 11 is a longitudinal sectional view of another particulate trap used in the exhaust emission control device of FIG.

FIG. 12 is a longitudinal sectional view of another particulate trap used in the exhaust emission control device of FIG.

FIG. 13 is an enlarged partial cross-sectional view in the longitudinal direction of another particulate trap used in the exhaust purification system of FIG.

FIG. 14 is a view on arrow E of FIG.

FIG. 15 is a longitudinal sectional view of another particulate trap used in the exhaust emission control device of FIG.

16 is an enlarged partial longitudinal cross-sectional view of another particulate trap used in the exhaust emission control device of FIG.

FIG. 17 is a view on arrow F of FIG.

FIG. 18 is an enlarged partial longitudinal cross-sectional view of another particulate trap used in the exhaust emission control device of FIG. 6.

19 is a cross-sectional view taken along line GG of FIG.

FIG. 20 is a partially enlarged longitudinal cross-sectional view of another particulate trap used in the exhaust emission control device of FIG.

21 is a view on arrow H of FIG. 20. FIG.

22 is an enlarged partial longitudinal cross-sectional view of another particulate trap used in the exhaust emission control device of FIG.

23 is a view on arrow I of FIG.

[Explanation of symbols]

1 ... Engine exhaust passage 2,4 ... Particulate trap 3 ... Communication pipe 20, 40, 60, 60 '... Trap passage 50, 50'70, 70 '... communication passage p: Particulate trap means area q ... communication means area

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-4-339120 (JP, A) JP-A-3-202605 (JP, A) JP-A-5-163930 (JP, A) Actual development Sho-58- 72414 (JP, U) Actual Kaihei 3-43520 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 3/02

Claims (6)

(57) [Claims] 1. A particulate trap means having a plurality of trap passages capable of passing a large amount of exhaust gas, and a communicating means having a plurality of communicating passages capable of passing a large amount of exhaust gas, Each of the trap passages of the particulate trap means has a trap wall extending in the longitudinal direction as at least one side wall, and allows exhaust gas to pass through the trap wall. The particulate trap means and the communicating means. And are arranged in parallel to each other in the engine exhaust system, and the particulate trap means
Is provided in the central part of the particulate trap,
Communication means are installed around the particulate trap.
The exhaust upstream side opening area of each of the communication passages
Is the opening area of each of the trap passages on the exhaust upstream side
By being smaller, the respective flow path resistance of the communication passage, an exhaust gas purifying apparatus for an internal combustion engine being greater than the respective flow resistance of the trap passage. 2. A large amount of exhaust gas having a plurality of trap passages.
A particulate trap means that allows gas to pass through
Communication hand that has a large number of communication passages and can pass a large amount of exhaust gas
Each of said particulate trap means comprising:
The trap passage has a trap wall extending in the longitudinal direction.
At least one side wall has the trap in the exhaust gas
It passes through a wall, and the particulate tiger
And the communication means are parallel to each other in the engine exhaust system.
Are arranged in the longitudinal direction of each of the communication passages.
From the longitudinal length of each of the trap passages
By increasing the length, the flow path resistance of each of the communication passages is increased.
The resistance is greater than the flow resistance of each of the trap passages.
Exhaust purification system of an internal combustion engine, characterized in that brewing. 3. A large amount of exhaust gas having a plurality of trap passages
A particulate trap means that allows gas to pass through
Communication hand that has a large number of communication passages and can pass a large amount of exhaust gas
Each of said particulate trap means comprising:
The trap passage has a trap wall extending in the longitudinal direction.
At least one side wall has the trap in the exhaust gas
It passes through a wall, and the particulate tiger
And the communication means are parallel to each other in the engine exhaust system.
And the flow path resistance of each of the communication passages.
Is greater than the flow resistance of each of the trap passages.
At least one of the trap passages is a trap wall
Only one part of the exhaust upstream side and exhaust downstream side
The trap wall of the at least one trap passage
At least one of the communication passages is adjacently arranged,
At least one communication passage is the at least one
Having a trap wall of the up passage as at least one side wall
Exhaust purification system of an internal combustion engine, characterized in that there. 4. A large amount of exhaust gas having a plurality of trap passages.
A particulate trap means that allows gas to pass through
Communication hand that has a large number of communication passages and can pass a large amount of exhaust gas
Each of said particulate trap means comprising:
The trap passage has a trap wall extending in the longitudinal direction.
At least one side wall has the trap in the exhaust gas
It passes through a wall, and the particulate tiger
And the communication means are parallel to each other in the engine exhaust system.
Located on the exhaust of the two adjacent communication passages.
The partition wall between the flow side openings is thickened to allow exhaust gas to flow through the partition wall.
To make it difficult for them to flow into the adjacent communication passage.
Therefore, the flow path resistance of each of the communication passages is
An exhaust gas purifying apparatus for an internal combustion engine, wherein the flow path resistance of each of the up passages is larger than that of the up passage . 5. A large amount of exhaust gas having a plurality of trap passages.
A particulate trap means that allows gas to pass through
Communication hand that has a large number of communication passages and can pass a large amount of exhaust gas
Each of said particulate trap means comprising:
The trap passage has a trap wall extending in the longitudinal direction.
At least one side wall has the trap in the exhaust gas
It passes through a wall, and the particulate tiger
And the communication means are parallel to each other in the engine exhaust system.
Located on the exhaust upstream side of each of the communication passages.
The end faces are the exhaust upstream side end faces of the trap passages.
Since it is located on the upstream side of the exhaust gas,
The respective flow path resistances of the
Is larger than the flow resistance of the exhaust gas. 6. A large amount of exhaust gas having a plurality of trap passages.
A particulate trap means that allows gas to pass through
Communication hand that has a large number of communication passages and can pass a large amount of exhaust gas
Each of said particulate trap means comprising:
The trap passage has a trap wall extending in the longitudinal direction.
Has at least as one side wall, the trap in the exhaust gas
It passes through a wall, and the particulate tiger
And the communication means are parallel to each other in the engine exhaust system.
Are located in two adjacent trap passages.
Between the openings on the exhaust upstream side, there is a tapered projection that protrudes to the exhaust upstream side.
Exhaust gas is forwarded by the tapered projection shape.
By making it easier to flow into the adjacent trap passage,
The flow path resistance of each of the communication paths is determined by the trap path.
An exhaust gas purification apparatus for an internal combustion engine, wherein the flow path resistances are larger than the respective flow resistances .