JP2003201821A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine equipped with a particulate filter, which suppresses deterioration of the exhaust emission and a rise of the exhaust resistance, and recovers or maintaining the performance of the particulate filter. <P>SOLUTION: The amount of the particulates in the exhaust gas downstream of the particulate filter increases while the performance of the filter is maintained or recovered. Downstream of the filter, a sweeper 45 is installed so as to capture the particulates. The sweeper is furnished with exhaust gas passages 57 and 58 partitioned by porous bulkheads 59, and the bulkheads to partition the end of at least one of the exhaust gas passages are formed aslant so that they approach each other. Small holes 55 and 56 are formed at the end of the passage by the slant bulkheads 52 and 53 and the ends of the passages are blocked partially. The flowing section area of each small hole is smaller than that of the passage and greater than the pores of the bulkheads. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device for an internal combustion engine.

[0002]

2. Description of the Related Art It is known to arrange an exhaust purification device for purifying components in exhaust gas discharged from an internal combustion engine in an engine exhaust passage. For example, JP 2000-50
Japanese Patent No. 031 discloses an exhaust gas purification device having a particulate filter in an engine exhaust passage for collecting fine particles in exhaust gas discharged from a compression ignition type internal combustion engine. In this exhaust emission control device, the particulate filter merely collects the fine particles, that is, the particulate filter itself cannot remove the collected fine particles. For this reason, when the usage period is long, the particulate filter is clogged with the particles. That is, the performance of the particulate filter deteriorates.

Therefore, in this exhaust gas purifying apparatus, in order to recover the performance of the particulate filter that has deteriorated, almost all of the exhaust gas bypasses the particulate filter, and only a small amount of the exhaust gas flows into the particulate filter. After that, the fine particles collected in the particulate filter are removed by burning the fine particles collected in the particulate filter by the electric heater provided in the particulate filter. The reason why almost all of the exhaust gas bypasses the particulate filter here is to promote the combustion of the particulates trapped in the particulate filter.

Further, in Japanese Patent Laid-Open No. 2000-18026.
Is the nitrogen in the exhaust gas discharged from the compression ignition type internal combustion engine.
Elemental oxide (NO_x ) NO for reducing and purifying_x Catalyst
An exhaust gas purification device provided in an engine exhaust passage is disclosed.
It NO of this exhaust purification system_xThe catalyst is NO in the exhaust gas_x
 Is temporarily stored and is stored at a predetermined time.
NO_x NO by reducing_x Reduce and purify
I am trying. However, this NO_x Exhaust gas for the catalyst
Sulfur oxides (SO_x ) Adheres to this SO _x With
When the amount of wear increases, NO_x The catalyst can occlude
NO_x Is reduced, resulting in NO_x N of catalyst
O_x The purification rate will decrease. That is, NO_x Catalytic
Performance will decrease.

Therefore, in this exhaust emission control device,
NO_x NO to restore catalyst performance_x Flow into the catalyst
After reversing the flow of exhaust gas,_x From the catalyst
SO _x Is trying to get rid of. Note that NO here
_x The reverse of the flow of exhaust gas flowing into the catalyst is N
O_x SO from catalyst_x This is to promote the withdrawal of.

The invention described in Japanese Patent Laid-Open No. 2000-18026 is not applicable only for releasing SO _x adhering to a NO _x catalyst, and for example, traps fine particles in exhaust gas. It is disclosed that it is also applicable to remove the component adhered to the particulate filter for removing from the particulate filter.
That is, according to this, in order to recover the performance of the particulate filter that has deteriorated, the flow of the exhaust gas that flows into the particulate filter is reversed, and the component that deteriorates the performance of the particulate filter is reduced. Will be forced to leave.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the exhaust gas purifying apparatus disclosed in Japanese Patent Application Laid-Open No. 001-50031, when recovering the performance of the deteriorated particulate filter, almost all the exhaust gas is exhausted in order to promote the combustion of the fine particles trapped in the particulate filter. The gas is allowed to bypass the particulate filter. However, while the exhaust gas is bypassed, the particulates in the exhaust gas are not collected by the particulate filter and are discharged downstream of the particulate filter. This is not preferable because it deteriorates exhaust emission.

Further, the above-mentioned Japanese Patent Laid-Open No. 2000-18026.
According to the exhaust emission control device disclosed in the publication, when recovering the performance of the deteriorated particulate filter,
The flow of the exhaust gas flowing into the particulate filter is reversed so as to promote the separation of the components adhering to the particulate filter. However, in general,
The fine particles in the exhaust gas tend to be collected on the wall surface on the upstream side in the particulate filter. Therefore, when the flow of the exhaust gas flowing into the particulate filter is reversed, the particulates trapped in the particulate filter are likely to separate from the wall surface and flow out from the particulate filter. This is not preferable because it deteriorates exhaust emission.

As described above, in order to recover the lowered performance of the particulate filter, the combustion of the particulates trapped in the particulate filter is promoted, or the components adhering to the particulate filter are released. Exhaust emission may be deteriorated by executing the control for promoting the engine.

Of course, the above-mentioned Japanese Patent Laid-Open No. 2000-180.
Japanese Patent Laid-Open No. 26-26 discloses that a sweeper for capturing or purifying components in exhaust gas is arranged downstream of the particulate filter to suppress deterioration of exhaust emission. Although the structure of the sweeper is not described in detail in this publication, the sweeper generally has a large number of exhaust flow passages for passing exhaust gas, and these exhaust flow passages are defined by partition walls. .

Here, in order to improve the capture rate or purification rate of the components in the exhaust gas by the sweeper, for example,
The partition wall may be formed of a porous material, and the upstream end opening or the downstream end opening of the exhaust flow passage of the sweeper may be closed with, for example, a plug so that the exhaust gas passes through the pores of the partition wall. However, this is not preferable because the exhaust resistance increases and the output efficiency of the internal combustion engine deteriorates. Of course, an increase in exhaust resistance cannot be suppressed just by forming a through hole in the plug.

On the other hand, in order to reduce the exhaust resistance,
For example, the exhaust gas may flow out from the sweeper only through the exhaust flow passage without blocking the upstream end opening and the downstream end opening of the exhaust flow passage of the sweeper. However, this is not preferable because the capture rate or purification rate of the components in the exhaust gas by the sweeper becomes low and the exhaust emission deteriorates.

As described above, in the exhaust gas purifying apparatus having the particulate filter, the means for recovering or maintaining the performance of the particulate filter suppresses the deterioration of the exhaust emission and increases the exhaust resistance. Is also required to be suppressed.

Therefore, an object of the present invention is to recover the performance of a particulate filter in an exhaust gas purification apparatus equipped with a particulate filter while suppressing deterioration of exhaust emission and suppressing an increase in exhaust resistance, or It is to provide a means that can be maintained.

[0015]

In order to solve the above problems, in the first invention, a particulate filter for collecting fine particles in exhaust gas and the performance of the particulate filter are maintained, or A performance maintaining / recovering means for recovering the performance of the particulate filter is maintained or recovered by the performance maintaining / recovering means. In an exhaust emission control device with an increased amount, a sweeper capable of collecting fine particles in exhaust gas is provided downstream of the particulate filter, and the sweeper is defined by a plurality of partition walls extending from the upstream side to the downstream side. The sweeper has an exhaust flow passage extending from upstream to downstream, and the partition wall of the sweeper is formed of a porous material having pores. The partition walls defining at least one of the upstream end and the downstream end of at least one exhaust flow passage of the exhaust gas flow passage are inclined so as to come close to each other, and the exhaust flow passage is formed by the inclined partition walls. A small hole is defined at the upstream end or the downstream end of the exhaust passage, and the upstream end or the downstream end of the exhaust flow passage is partially closed, and the passage of the small hole is defined by the slanted partition wall. The area is smaller than the flow passage cross-sectional area of the exhaust flow passage of the sweeper and larger than the flow passage cross-sectional area of the pores of the partition wall. According to this, even if the performance of the particulate filter is maintained or restored by the performance maintaining / restoring means, even if the amount of particulates in the exhaust gas downstream of the particulate filter increases, such particulates will not be generated. Captured by the sweeper. The slanted partition wall is a tapered wall in an embodiment described later.

In the second invention, in the first invention,
The small hole is defined by a partition wall which is slanted by bending and collecting the upstream end or the downstream end of the partition wall.

In the third invention, in the first invention,
The above particulate filter traps ambient oxygen when excess oxygen is present in the surroundings and releases trapped oxygen in the form of active oxygen when the ambient oxygen concentration decreases to produce active oxygen. The agent is carried, and the active oxygen generated by the active oxygen generating agent continuously oxidizes and removes the fine particles trapped in the particulate filter.

In the fourth invention, in the third invention,
NO _x which the active oxygen generating agent carried on the particulate filter oxygen concentration around and capture the NO _x when excess oxygen is present around entrapping the reduced
It has a NO _x reduction and purification capacity that can release and reduce and purify.

In a fifth aspect of the invention, in any one of the second to fourth aspects of the invention, an exhaust flow for reversing the exhaust gas inflow side into which the exhaust gas flows and the exhaust outflow side from which the exhaust gas flows out in the particulate filter. The performance maintaining / restoring means further includes a reverse rotation mechanism, and the performance of the particulate filter is maintained or restored by reversing the exhaust gas inflow side and the exhaust flow out side of the particulate filter by the exhaust flow reversal mechanism. . Here, the exhaust flow reversing mechanism is a switching valve in an embodiment described later.

In a sixth aspect of the invention, in any one of the first to fourth aspects of the invention, a bypass passage for bypassing the particulate filter to the exhaust gas, and generally almost the entire amount of the exhaust gas is allowed to flow into the particulate filter. However, there is a flow rate control valve that can adjust the amount of exhaust gas that flows into the particulate filter and the amount of exhaust gas that flows into the bypass passage, and a reduction for injecting a reducing agent into the particulate filter. The performance maintaining / recovering means causes at least a part of the exhaust gas to flow into the bypass passage by the flow rate control valve, and the reducing agent is injected from the reducing agent injection means to particulate. By supplying the reducing agent to the filter, the fine particles trapped in the particulate filter are collected. Maintaining the performance of the particulate filter by promoting oxidation of a child, or to recover.
Here, the reducing agent injection means is a reducing agent injection valve in an embodiment described later.

In the seventh invention, in any one of the first to sixth inventions, the sweeper captures ambient oxygen when excess oxygen is present in the ambient and captures it when ambient oxygen concentration is reduced. It carries an active oxygen generator that generates active oxygen by releasing oxygen in the form of active oxygen,
The fine particles trapped in the sweeper are continuously oxidized and removed by the active oxygen generated by the active oxygen generator.

In the eighth invention, in the seventh invention,
NO active oxygen generating agent, which is supported on the sweeper can the oxygen concentration of the captured and around the NO _x when excess oxygen is present to reduce and purify by releasing the NO _x entrapping the drops around _x Has reduction and purification capacity.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An exhaust emission control device of the present invention will be described below with reference to the drawings. FIG. 1 shows a case where the exhaust emission control device of the present invention is applied to a compression ignition type internal combustion engine. The exhaust emission control device of the present invention can also be applied to a spark ignition type internal combustion engine. Referring to FIG. 1, 1 is an engine body,
2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an electrically controlled fuel injection valve, 7 is an intake valve, 8 is an intake port, 9 is an exhaust valve, and 10 is an exhaust port. . The intake port 8 is connected to the surge tank 12 via a corresponding intake branch pipe 11. Surge tank 12
Is connected to the compressor 15 of the exhaust turbocharger 14 via the intake duct 13.

A step motor 16 is installed in the intake duct 13.
A throttle valve 17 driven by is arranged. Further, around the intake duct 13, a cooling device 18 for cooling the intake air flowing in the intake duct 13 is arranged.
In the embodiment shown in FIG. 1, the engine cooling water is guided into the cooling device 18, and the intake air is cooled by the engine cooling water. On the other hand, the exhaust port 10 is connected to an exhaust turbine 21 of an exhaust turbocharger 14 via an exhaust manifold 19 and an exhaust pipe 20. The outlet of the exhaust turbine 21 is connected to the exhaust purification device 22 of the present invention.

The exhaust manifold 19 and the surge tank 12 are connected to each other via an exhaust gas recirculation (hereinafter referred to as EGR) passage 24. An electrically controlled EG is installed in the EGR passage 24.
An R control valve 25 is arranged. A cooling device 26 for cooling the EGR gas flowing in the EGR passage 24 is arranged around the EGR passage 24. In the embodiment shown in FIG. 1, the engine cooling water is guided into the cooling device 26, and the EGR gas is cooled by the engine cooling water. On the other hand, each fuel injection valve 6 is connected to a fuel reservoir, a so-called common rail 27, via a fuel supply pipe 6a. Fuel is supplied to the inside of the common rail 27 from an electrically controlled fuel pump 28 having a variable discharge amount. The fuel supplied into the common rail 27 is supplied to the fuel injection valve 6 via each fuel supply pipe 6a. A fuel pressure sensor 29 for detecting the fuel pressure in the common rail 27 is attached to the common rail 27. Based on the output signal of the fuel pressure sensor 29, the discharge amount of the fuel pump 28 is controlled so that the fuel pressure in the common rail 27 becomes the target fuel pressure.

The electronic control unit 30 is composed of a digital computer, and has a ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, an input port 35, and an input port 35, which are connected to each other by a bidirectional bus 31. An output port 36 is provided. The output signal of the fuel pressure sensor 29 is input to the input port 35 via the corresponding AD converter 37.

The accelerator pedal 40 includes an accelerator pedal 4
A load sensor 41 that generates an output voltage proportional to the stepping amount L of 0 is connected. The output voltage of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37. Further, the input port 35 is connected to a crank angle sensor 42 that generates an output pulse each time the crankshaft rotates, for example, 30 °. On the other hand, the output port 36 is connected to the fuel injection valve 6, the throttle valve driving step motor 16, the EGR control valve 25, and the fuel pump 28 via the corresponding drive circuit 38.

FIG. 2 shows the exhaust purification system of the first embodiment. Referring to FIG. 2, two exhaust branch pipes, that is, a first exhaust branch pipe 20a and a second exhaust branch pipe 20b are branched from the exhaust pipe 20 downstream of the exhaust turbine 21 of the turbocharger 14. These exhaust branch pipes 20a and 20b join at the downstream of the region where they branch. That is, the exhaust branch pipes 20a and 20b form a loop-type exhaust passage. A particulate filter (hereinafter, simply referred to as a filter) 23 that can collect fine particles in the exhaust gas is arranged in the exhaust passage in a region where the exhaust branch pipes 20a and 20b join.

Further, in the exhaust pipe 20 in the region where the two exhaust branch pipes 20a and 20b are branched, the exhaust gas is caused to flow from the first exhaust branch pipe 20a to the filter 23, or
A switching valve 4 capable of selectively switching whether the exhaust branch pipe flows into the filter 23 from the second exhaust branch pipe 20b.
3 is arranged. A step motor 44 is connected to the switching valve 43. The step motor 44 corresponds to the corresponding drive circuit 3
8 to the output port 36. The stepping motor 44 allows the switching valve 43 to switch between the position shown in FIG. 2 (A) and the position shown in FIG. 2 (B).

When the switching valve 43 is in the position shown in FIG. 2A, the exhaust gas flows into the filter 23 through the first exhaust branch pipe 20a and passes through the filter 23 as shown by the arrow. And further outflows to the second exhaust branch pipe 20b,
Finally, it flows into the exhaust pipe 20 on the downstream side of the switching valve 43.
On the other hand, when the switching valve 43 is in the position shown in FIG. 2B, the exhaust gas flows into the filter 23 through the second exhaust branch pipe 20b and passes through the filter 23 as shown by the arrow. Further, it flows out to the first exhaust branch pipe 20a and finally flows into the exhaust pipe 20 on the downstream side of the switching valve 43. That is, by switching the operating state of the switching valve 43,
The flow direction of the exhaust gas flowing into the filter 23 is reversed.

FIG. 3 shows the filter of the present invention in detail.
3A is a front view of the filter 23, and FIG. 3B is a side sectional view of the filter 23. Figure 3
As shown in (A) and (B), the filter 23 has a honeycomb structure and is provided with a plurality of exhaust flow passages 50, 51 extending in parallel with each other. These exhaust flow passages are composed of an exhaust gas inflow passage 50 whose downstream end is closed by a plug 52 and an exhaust gas outflow passage 51 whose upstream end is closed by a plug 53.

The hatched portion in FIG. 3A shows the plug 53. Therefore, the exhaust gas inflow passages 50 and the exhaust gas outflow passages 51 are alternately arranged via the thin partition walls 54. In other words, in the exhaust gas inflow passage 50 and the exhaust gas outflow passage 51, each exhaust gas inflow passage 50 is surrounded by the four exhaust gas outflow passages 51,
Each exhaust gas outflow passage 51 has four exhaust gas inflow passages 50.
It is arranged so as to be surrounded by.

The filter 23 is formed of a porous material such as cordierite. Therefore, the exhaust gas that has flowed into the exhaust gas inflow passage 50 is generated as shown in FIG.
As indicated by the arrow in FIG. 3, the gas flows through the surrounding partition wall 54 into the adjacent exhaust gas outflow passage 51.

By the way, referring again to FIG. 2, in the exhaust pipe 20 on the downstream side of the switching valve 43, a sweeper 45 capable of collecting fine particles in the exhaust gas is arranged. Figure 4
The sweeper of the present invention is shown in detail in FIG. 4A is an end view of the sweeper 45, and FIG. 4B is a vertical sectional view of the sweeper 45.

As shown in FIGS. 4A and 4B, the sweeper 45 has a honeycomb structure and is provided with a plurality of exhaust flow passages 57 and 58 extending in parallel with each other. Almost half of these exhaust flow passages form the exhaust gas inflow passage 57, and the remaining half form the exhaust gas outflow passage 58. The exhaust gas inflow passages 57 and the exhaust gas outflow passages 58 are alternately arranged via thin partition walls 59. In other words, in the exhaust gas inflow passage 57 and the exhaust gas outflow passage 58, each exhaust gas inflow passage 57 is surrounded by four exhaust gas outflow passages 58, and each exhaust gas outflow passage 58 is surrounded by four exhaust gas inflow passages 57. It is arranged as described.

The exhaust gas inflow passage 57 is slanted so that the downstream end openings thereof are close to each other, and a partition wall 59 defining the small hole 55 at the tip, that is, the tapered wall 5 having the small hole 55 is formed.
It is partially blocked by 2. On the other hand, the exhaust gas outflow passage 58 is partially blocked by a partition wall 59 that is slanted so that its upstream end openings are close to each other and defines a small hole 56 at the tip, that is, a tapered wall 53 having the small hole 56. There is. Broadly defined, in the present invention, a part of the exhaust flow passage 57 is partially blocked by the tapered wall 52 at the downstream end thereof, and the small hole 55 is formed at the tip of the tapered wall 52. On the other hand, the remaining exhaust flow passage 58 is partially closed at its upstream end by the tapered wall 53, and a small hole 56 is formed at the tip of this tapered wall 53.

Here, in the present invention, the small holes 55, 56.
Is smaller than the size of the exhaust flow passages 57 and 58 (flow passage cross-sectional area), and the size of the pores of the tapered walls 52 and 53 formed by the partition walls 59 (flow passage cut-off). area)
Greater than.

The tapered wall 52 defines the exhaust gas inflow passage 57 in the manufacturing process of the sweeper 45.
It is formed by bending and deforming the downstream end portions of 9 and bringing them together. On the other hand, the tapered wall 53 defines the exhaust gas outflow passage 58 in the manufacturing process of the sweeper 45.
It is formed by bending and deforming the upstream end portions of 9 and gathering them together.

The sweeper 45 is made of a porous material such as cordierite. Therefore, the exhaust gas that has flowed into the exhaust gas inflow passage 57 passes through the surrounding partition wall 59 and flows into the adjacent exhaust gas outflow passage 58, as indicated by the arrow in FIG. 4B.

Of course, the tapered walls 52 and 53 are also the partition walls 59.
Since the exhaust gas is formed of the same porous material as that shown in FIG. 4B, the exhaust gas flows into the exhaust gas outflow passage 58 through the tapered wall 53 as shown by the arrow in FIG. ), It flows out from the exhaust gas inflow passage 57 through the tapered wall 52. As described above, since the exhaust gas can be passed through the portions 52 and 53 that block the exhaust flow passage of the sweeper 45, the pressure loss of the sweeper 45 is low.

Further, the exhaust gas can flow into the exhaust gas outflow passage 58 through the small hole 56 formed at the tip of the tapered wall 53. In addition, the exhaust gas is tapered wall 52.
It can also flow out from the exhaust gas inflow passage 57 through the small hole 55 at the tip of the. In this way, the tapered walls 52, 53
Since the small hole 56 at the tip of the can pass exhaust gas,
From this, it can be said that the pressure loss of the sweeper 45 of the present invention is low.

The taper wall 52 that closes the exhaust gas inflow passage 57 at the downstream end has an outlet of an exhaust gas outflow passage 58 formed by being surrounded by the four taper walls 52, and the flow passage is cut off toward the downstream side. The flow passage cross-sectional area is gradually reduced toward the downstream side so that the area gradually increases and becomes a conical shape. According to this, as shown in FIG. 5B, the exhaust gas is more likely to flow out from the sweeper than in the case where the outlet of the exhaust gas outflow passage is configured.

That is, in the sweeper shown in FIG. 5B, the downstream end opening of the exhaust gas inflow passage is closed by the plug 70, and the exhaust gas outflow passage extends linearly to the outlet. In this case, a part of the exhaust gas flowing out from the outlet of the exhaust gas outflow passage flows along the downstream end face of the plug 70, so that a turbulent flow 71 is formed near the outlet of the exhaust gas outflow passage. When the turbulent flow is formed in this way, it becomes difficult for the exhaust gas to flow out from the exhaust gas outflow passage.

On the other hand, in the sweeper 45 of the present invention, as shown in FIG.
As shown in (B), the exhaust gas can smoothly flow out from the exhaust gas outflow passage 58 without becoming a turbulent flow. For this reason, according to the present invention, the exhaust gas easily flows out from the sweeper 45. Therefore, it can be said that the pressure loss of the sweeper 45 of the present invention is also low.

On the other hand, the tapered wall 53 that closes the exhaust gas outflow passage 58 at the upstream end has an exhaust gas inflow passage 57 formed by being surrounded by the four tapered walls 53, and the inlet of the exhaust gas inflow passage 57 flows upward. The flow passage cross-sectional area gradually decreases toward the upstream side so that the cross-sectional area gradually increases and becomes a conical shape. According to this, as compared with the case where the inlet of the exhaust gas inflow passage is configured as shown in FIG. 5 (A), the exhaust gas easily flows into the sweeper.

That is, in the sweeper shown in FIG. 5A, the upstream end opening of the exhaust gas outflow passage is closed by the plug 72. In this case, since a part of the exhaust gas collides with the plug 72 as indicated by 73, the pressure loss due to the sweeper becomes large. Further, the exhaust gas flowing from the vicinity of the plug 72 into the exhaust gas inflow passage becomes a turbulent flow near the inlet, as indicated by 74, so that the exhaust gas becomes difficult to flow into the exhaust gas inflow passage.

On the other hand, in the sweeper 45 of the present invention, FIG.
As shown in (A), the exhaust gas can smoothly flow into the exhaust gas inflow passage 57 without becoming a turbulent flow. For this reason, according to the present invention, the exhaust gas relatively easily flows into the sweeper 45. Therefore, also by this, it can be said that the pressure loss of the sweeper 45 of the present invention is low.

Further, in the sweeper shown in FIG. 5, a large amount of fine particles in the exhaust gas are easily deposited on the upstream end surface of the plug 72 and the surface of the partition wall in the vicinity thereof. This is the exhaust gas plug 72
And the exhaust gas becomes a turbulent flow in the vicinity of the plug 72. However, in the sweeper 45 of the present invention, since the tapered wall 53 has a conical shape, there is no upstream end face against which exhaust gas collides strongly, and the exhaust gas does not become turbulent near the upstream end face. Therefore, according to the present invention, a large amount of fine particles are not deposited in the upstream end region of the sweeper 45.

As described above, according to the sweeper 45 of the present invention, the small holes 55 and 56 are provided at the tips of the tapered walls 52 and 53, and the tapered walls 52 and 53 are formed at a small angle with respect to the exhaust gas flow direction. By tilting,
The pressure loss can be greatly reduced without significantly reducing the collection rate of fine particles.

The tapered walls 52 and 53 are formed by the sweeper 45.
The shape may be, for example, a conical shape, a quadrangular pyramid shape, or a hexagonal pyramid shape, as long as it has a shape that gradually narrows toward the outside. Also, by adjusting the size of the small holes 55, 56,
The particulate collection rate of the sweeper 45 can be changed. Further, the sweeper 45 of the present embodiment is a type of sweeper having small holes on both end surfaces thereof. For example, a sweeper of a type having a small hole only on one side end, or a small hole only on a part of the end surface. It can be a type of sweeper. Of course, the structure of the filter 23 may be similar to that of the sweeper 45.

Next, the operation of the exhaust purification system of this embodiment will be described. The filter 23 collects the particulates in the exhaust gas as described above, but in the present embodiment, in addition to this, the filter 23 continuously collects the collected particulates in a short time without emitting a bright flame. It can be removed by oxidation. The oxidation removing action of the filter 23 will be described later in detail.

According to the filter 23 of the present embodiment, as long as a certain condition is satisfied, the fine particles just collected by the filter 23 are deposited, but these fine particles remain in a short time. Completely removed by oxidation. Therefore, as long as a certain fixed condition is satisfied, only a certain amount of fine particles or less are deposited on the filter 23, and the pressure loss of the filter 23 is suppressed to a low level.

However, depending on the conditions, the filter 23
In some cases, a certain amount or more of fine particles may be deposited. In this case, the pressure loss of the filter 23 becomes larger than the expected value, which is not preferable. Therefore, in the present invention, the operation state of the switching valve 43 is switched when a predetermined condition is satisfied. According to this, the direction of the exhaust gas flowing into the filter 23 is reversed, whereby the partition wall 54 is
Of the wall or the wall that defines the pores of the partition wall 54 is separated from the wall, and as a result, the particle is made to flow in the filter 23.

In general, it is considered that the fine particles trapped in the area that is difficult to be oxidized and removed are often deposited in the filter 23. Here, as described above, by causing the fine particles to flow in the filter 23, the fine particles that have accumulated move to a region that is more easily removed by oxidation, so that the fine particles that have accumulated on the filter 23 are oxidized. Will be removed.

That is, once the fine particles start to be deposited on the filter 23, the fine particles are successively deposited, and as a result,
Although the particulate oxidation removal capability of the filter 23, that is, the performance of the filter 23 is reduced, according to the present invention, the filter 23 is used to maintain the performance of the filter 23 or to recover the degraded performance of the filter 23. The direction of the inflowing exhaust gas is reversed.

When the direction of the exhaust gas flowing into the filter 23 is reversed in this way, depending on the case,
In some cases, the particulates may be exfoliated from the wall surface of the filter 23 at once, and some of the exfoliated particulates may not be oxidized and removed in the filter 23 and may flow out from the filter 23, resulting in deterioration of exhaust emission. Immediately after reversing the direction of the exhaust gas flowing into the filter 23, when the internal combustion engine is accelerated and the amount of exhaust gas increases, particulates may flow out from the filter 23 and exhaust emission may deteriorate. high.

However, according to the present invention, the sweeper 45 is arranged downstream of the filter 23, and the fine particles flowing out from the filter 23 are collected by the sweeper 45. Therefore, according to the present invention, deterioration of exhaust emission is suppressed.

Of course, as described above, the structure of the sweeper 45 of the present invention is a structure in which the pressure loss can be significantly reduced without significantly lowering the particulate collection rate, so the sweeper 45 is arranged downstream of the filter 23. Even in this case, the pressure loss of the entire exhaust purification device does not increase significantly, and the sweeper 45 improves the particulate collection rate of the entire exhaust purification device.

The sweeper 45 of the present invention also has the ability to oxidize and remove the collected fine particles continuously in a short time without emitting a bright flame. Therefore, by disposing the sweeper 45 downstream of the filter 23, the particulate removal rate of the entire exhaust gas purification device is improved without significantly increasing the pressure loss of the entire exhaust gas purification device.

Next, the structure of the filter and sweeper of the present invention for removing fine particles will be described. In the present embodiment, the sweeper particulate removal configuration is the same as that of the filter, so only the particulate removal configuration of the filter will be described below.

Peripheral wall surfaces of each exhaust gas inflow passage 50 and each exhaust gas outflow passage 51, that is, on both side wall surfaces of each partition wall 54 and on the wall surface defining the pores of each partition wall (in the sweeper 45, In addition to the tapered walls 52, 53
On both side wall surfaces and on the wall surfaces defining the pores of the tapered walls 52 and 53), a layer of a carrier made of, for example, alumina is formed, and the active oxygen generator and the noble metal are formed on this carrier. A catalyst is supported. The active oxygen generator of the present invention captures oxygen when excess oxygen exists in the surroundings and releases the captured oxygen in the form of active oxygen when the ambient oxygen concentration decreases to generate active oxygen.

In the present invention, platinum Pt is used as the noble metal catalyst, and as the active oxygen generator, potassium K, sodium Na, lithium Li, cesium Cs, alkali metals such as rubidium Rb, barium Ba, calcium Ca, strontium. Alkaline earth metals such as Sr, lanthanum La, yttrium Y, rare earths such as cerium Ce, transition metals such as iron Fe, and tin Sn.
At least one selected from the following carbon group elements is used.

As the active oxygen generator, alkali metal or alkaline earth metal having a higher ionization tendency than calcium Ca, that is, potassium K, lithium L
It is preferable to use i, cesium Cs, rubidium Rb, barium Ba, and strontium Sr.

Next, regarding the fine particle removing action of the filter 23 of the present invention, platinum Pt and potassium K are deposited on the carrier.
The case of supporting the above will be described as an example, but the same fine particle removing action can be achieved by using other noble metals, alkali metals, alkaline earth metals, rare earths, and transition metals. Of course, the sweeper 45 also removes fine particles from the filter 2
It is the same as the fine particle removing action by 3.

When the ratio of the air supplied to the intake passage and the combustion chamber 5 to the fuel is called the air-fuel ratio of the exhaust gas, the air-fuel ratio of the exhaust gas discharged from the compression ignition type internal combustion engine is lean. That is, the exhaust gas discharged from the compression ignition type internal combustion engine contains a large amount of excess air. Further, NO is generated in the combustion chamber of the compression ignition type internal combustion engine. Therefore, NO is contained in the exhaust gas. Further, the fuel contains a sulfur component S, and this sulfur component S reacts with oxygen in the combustion chamber to become SO ₂ . Therefore, the exhaust gas contains SO ₂ . For this reason, the exhaust gas containing excess oxygen, NO, and SO ₂ is filtered by the filter 2
3 into the exhaust gas inflow passage 50.

7A and 7B schematically show enlarged views of the surface of the carrier layer formed on the peripheral wall surface of the exhaust gas inflow passage 50. 7 (A) and 7 (B)
In the above, 60 represents particles of platinum Pt, and 61 represents an active oxygen generator containing potassium K.

As described above, since the exhaust gas contains a large amount of excess oxygen, when the exhaust gas flows into the exhaust gas inflow passage 50 of the filter 23, as shown in FIG. 7 (A). The oxygen O ₂ adheres to the surface of platinum Pt in the form of O ₂ ⁻ or O ²⁻ . On the other hand, NO in the exhaust gas reacts with O ₂ ⁻ or O ^{2 −} on the surface of platinum Pt to become NO ₂ (2NO + O ₂ → 2NO ₂ ). Then the generated NO
Part of ₂ is oxidized on platinum Pt while active oxygen generator 6
7 is trapped by being absorbed in 1 and bound to potassium K as shown in FIG.
It diffuses in the form of ₃ ^{− into} the active oxygen generator 61 and produces potassium nitrate KNO ₃ . That is, as a result, oxygen in the exhaust gas is captured in the active oxygen generator 61 in the form of potassium nitrate KNO ₃ .

On the other hand, as described above, the exhaust gas contains S.
O _{2 is} also contained, and this SO ₂ is also captured by being absorbed in the active oxygen generator 61 by the same mechanism as NO. That is, as described above, oxygen O ₂ is attached to the surface of platinum Pt in the form of O ₂ ⁻ or O ^{2 −} ,
SO ₂ in the exhaust gas is O ₂ ⁻ or O ^{2 − on} the surface of platinum Pt.
And becomes SO ₃ . Then, a part of the generated SO ₃ is further oxidized on the platinum Pt while the active oxygen generating agent 6 is added.
It is captured by being absorbed in 1 and binds with potassium K to form an active oxygen generator 6 in the form of sulfate ion SO ₄ ²⁻
Diffuse into 1 to produce potassium sulfate K ₂ SO ₄ . That is, as a result, the oxygen in the exhaust gas is potassium sulfate K.
It is trapped in the active oxygen generator 61 in the form of ₂ SO ₄ .

On the other hand, in the combustion chamber 5, fine particles mainly composed of carbon C are produced. Therefore, the exhaust gas contains these fine particles. These fine particles contained in the exhaust gas are generated when the exhaust gas is flowing in the exhaust gas inflow passage 50 of the filter 23 or the partition wall 5
6B, when it passes through the pores of No. 4 in FIG.
As shown in (3), the surface of the carrier layer, for example, the surface of the active oxygen generating agent 61 is contacted and attached.

In this way, the fine particles 62 are the active oxygen generator 6
When it adheres to the surface of No. 1, the oxygen concentration decreases at the contact surface between the fine particles 62 and the active oxygen generator 61. When the oxygen concentration decreases, a difference in concentration occurs between the active oxygen generating agent 61 and the active oxygen generating agent 61 having a high oxygen concentration. Try to move towards. As a result, potassium nitrate KNO ₃ formed in the active oxygen generator 61 is decomposed into potassium K, oxygen O and NO, and oxygen O moves toward the contact surface between the fine particles 62 and the active oxygen generator 61, and one of them Thus, NO is released from the active oxygen generator 61 to the outside. The NO released to the outside is oxidized on the platinum Pt on the downstream side and captured again in the active oxygen generator 61.

At this time, the potassium sulfate K ₂ SO ₄ formed in the active oxygen generator 61 is also decomposed into potassium K, oxygen O and SO _2, and the oxygen O is separated from the fine particles 62 and the active oxygen generator 61. towards the contact surface, on the other hand, SO ₂
Are released from the active oxygen generator 61 to the outside. The SO ₂ released to the outside is oxidized on the platinum Pt on the downstream side and captured again in the active oxygen generator 61. However,
Since potassium sulfate K ₂ SO ₄ is stable and difficult to decompose, potassium sulfate K ₂ SO ₄ is less likely to release oxygen than potassium nitrate KNO ₃ .

By the way, the fine particles 62 and the active oxygen generator 61
Oxygen O toward the contact surface with is oxygen decomposed from a compound such as potassium nitrate KNO ₃ or potassium sulfate K ₂ SO ₄ . Oxygen O decomposed from the compound in this way has an unpaired electron and has extremely high reactivity. Therefore, oxygen toward the contact surface between the fine particles 62 and the active oxygen generator 61 is active oxygen O. Similarly, the reaction process of NO and oxygen in the active oxygen generator 61, or
Oxygen generated in the reaction process of SO ₂ and oxygen is also active oxygen. That is, the active oxygen generator 61 is NO
Nitrate ions NO ₃ ^- when captured in the form of, or, SO
Even ₂ when captured by sulfate ions SO ₄ ^2-form, to produce an active oxygen.

When these active oxygen O come into contact with the fine particles 62, the fine particles 62 are oxidized in a short time (several seconds to tens of minutes) without emitting a luminous flame, and the fine particles 62 disappear completely. Therefore, the fine particles 62 rarely deposit on the filter 22.

When the particulates accumulated in a laminated form on the filter 23 are removed by combustion as in the prior art, the filter 23 becomes red hot and the particulates burn with a flame. Combustion with such a flame does not last until it is hot. Therefore, the temperature of the filter 23 must be maintained at a high temperature in order to continue the combustion accompanied by the flame.

On the other hand, in the present invention, as described above, the fine particles 62 are oxidized without emitting a luminous flame. At this time, the surface of the filter 22 does not glow red. In other words, in the present invention, the fine particles 62 are oxidatively removed at a temperature considerably lower than the conventional temperature.
Therefore, the effect of removing fine particles 62 that does not emit a bright flame by the present invention is completely different from the effect of removing fine particles by the conventional combustion involving a flame.

By the way, platinum Pt and active oxygen generator 6
The activity of 1 depends on the temperature of the filter 23. Therefore, the maximum amount of fine particles that can be oxidized and removed in the filter 23 per unit time without emitting a luminous flame (the amount of fine particles that can be oxidized and removed) changes depending on the temperature of the filter 23. FIG. 8 shows the amount of fine particles that can be oxidized and removed by the filter 23.

The solid line in FIG. 8 indicates the temperature of the filter 23 (hereinafter,
The amount G of fine particles that can be removed by oxidation, which changes according to TF (referred to as filter temperature), is shown. Filter 2 per unit time
If the amount of fine particles flowing into 3 is called the amount M of inflowing fine particles,
When the amount M of inflowing fine particles is less than the amount of fine particles G that can be removed by oxidation, that is, when all the fine particles that have flowed into the filter 23 come into contact with the filter 23 in the region I of FIG. 8, a short time (from several seconds to several tens of minutes) is reached. In the filter 23
It is oxidised and removed without emitting a bright flame on the top.

On the other hand, when the amount M of inflowing fine particles is larger than the amount G of fine particles that can be removed by oxidation, that is, in the region of FIG.
In II, the amount of active oxygen is insufficient to oxidize all the fine particles. 9 (A) to 9 (C) show how the fine particles are oxidized in such a case. That is, when the amount of active oxygen is insufficient to oxidize all the fine particles, as shown in FIG. 9A, when the fine particles 62 adhere to the active oxygen generator 61, the amount of the fine particles 62 is reduced. Only the part is oxidized, and the part of the fine particles which is not sufficiently oxidized remains on the carrier layer. Next, when the state in which the amount of active oxygen is insufficient continues, the fine particle portions that are not oxidized one after another remain on the carrier layer, and as a result, as shown in FIG. The surface of the is covered with the residual fine particle portion 63.

If the surface of the carrier layer is covered with the residual fine particle portion 63, NO and SO ₂ oxidizing action of platinum Pt and active oxygen producing action of the active oxygen producing agent 61 become difficult to perform, and moreover, Even if these oxidizing and generating actions are performed, the residual fine particle portion 63
Is separated from platinum Pt, so that it is hard to receive the oxidation effect of platinum Pt. Therefore, the residual fine particle portion 63 remains as it is without being oxidized,
Next, the fine particles 64 deposited on the residual fine particle portion 63.
Also remains unoxidized for the same reason. Thus, as shown in FIG. 9C, another particle 64 is deposited on the residual particle portion 63 one after another. That is, the fine particles are deposited in a laminated form.

When the fine particles are deposited in a laminated form in this way,
The fine particles 64 are no longer oxidized by the active oxygen O, so that further fine particles are successively deposited on the fine particles 64. That is, the inflowing particle amount M
If the state in which the amount is larger than the amount G of oxidizable / removable particulates continues, the particulates are deposited in a layered manner on the filter 23, and thus the exhaust gas temperature is raised to a high temperature or the filter 23
Unless the temperature itself is set to a high temperature, the deposited particles cannot be ignited and burned.

As described above, in the region I of FIG. 8, the fine particles are oxidized on the filter 23 in a short time without emitting a bright flame. In the region II of FIG. 8, the fine particles are laminated on the filter 23. accumulate. Therefore, in order to prevent the particles from accumulating in a stacked state on the filter 23, the inflowing particle amount M needs to be always smaller than the oxidatively removable particle amount G.

As can be seen from FIG. 8, the filter 2 of the present invention.
3, it is possible to oxidize the fine particles even when the filter temperature TF is considerably low, and as a result, the inflowing fine particle amount M
Further, the filter temperature TF is maintained such that the inflowing particulate amount M is always smaller than the oxidatively removable particulate amount G. Thus, when the amount M of inflowing particles is always smaller than the amount G of particles that can be removed by oxidation, almost no particles are deposited on the filter 23, and thus the back pressure hardly increases.

Further, as described above, once the fine particles are deposited in a laminated form on the filter 23, even if the inflowing fine particle amount M becomes smaller than the oxidatively removable fine particle amount G, the fine particles are oxidized by the active oxygen O. It is difficult to get it done. However, when the unoxidized fine particle portion begins to remain, that is, when the fine particles are accumulated below a certain limit, the inflow fine particle amount M
Is smaller than the amount G of oxidatively removable fine particles, the residual fine particle portions are oxidatively removed by the active oxygen O without emitting a luminous flame.

Therefore, in the present invention, the amount M of inflowing fine particles is usually smaller than the amount G of fine particles that can be removed by oxidation, but it is assumed that the amount M of inflowing fine particles temporarily becomes larger than the amount G of fine particles that can be removed by oxidation. Also, as shown in FIG. 9 (B), the surface of the carrier layer is not covered with the residual fine particle portion 63, that is, when the amount M of inflowing fine particles becomes smaller than the amount G of fine particles that can be removed by oxidation, it is removed by oxidation. The amount M of inflowing fine particles and the filter temperature TF are maintained so that only a fine amount of fine particles less than a certain limit is deposited on the filter 23.

However, even if the inflowing particulate amount M and the filter temperature TF are controlled in this manner, the particulates may be deposited on the filter 23 in a laminated form. Therefore, in the present invention, in such a case, the operating state of the switching valve 43 is switched, and the direction of the exhaust gas flowing into the filter 23 is reversed, whereby the fine particles accumulated in the filter 23 are separated from the wall surface. Thus, the fine particles are made to flow in the filter 23. According to this, a certain amount or more of fine particles are not deposited in the filter 23.

If the direction of the exhaust gas flowing into the filter 23 is reversed and the air-fuel ratio of a part or the whole of the exhaust gas flowing into the filter 23 is temporarily made rich, Therefore, it is possible to suppress the accumulation of a certain amount or more of fine particles in the filter 23.

That is, if the state where the air-fuel ratio of the exhaust gas is lean continues for a certain period, a large amount of oxygen adheres to the platinum Pt, which lowers the catalytic action of the platinum Pt. However, when the air-fuel ratio of the exhaust gas is made rich to reduce the oxygen concentration in the exhaust gas, oxygen is removed from the platinum Pt, and thus the catalytic action of platinum Pt is restored. As a result, when the air-fuel ratio of the exhaust gas is made rich, the active oxygen O is easily released from the active oxygen generator 61 to the outside at once. Thus, the active oxygen O released all at once
As a result, the deposited fine particles are transformed into a state in which they are easily oxidized, and the fine particles are burned and removed by the active oxygen without emitting a bright flame. Thus, when the air-fuel ratio of the exhaust gas is made rich, the amount of fine particles G that can be oxidized and removed as a whole G
Will increase. Therefore, the fine particles deposited on the filter 22 are oxidized and removed without emitting a luminous flame.

FIG. 10 shows an exhaust purification system of a second embodiment of the present invention. Referring to FIG. 10, in the second embodiment, the filter 23 is arranged inside the exhaust pipe 20 downstream of the exhaust turbine 21 of the turbocharger 14. Further, in the second embodiment, the sweeper 45 is arranged in the exhaust pipe 20 downstream of the filter 23.

Further, a bypass passage 65 branches from the exhaust pipe 20 downstream of the exhaust turbine 21 and upstream of the filter 23. The bypass passage 65 is connected to the exhaust pipe 20 downstream of the filter 23 and upstream of the sweeper 45.
A flow rate control valve capable of adjusting the amount of exhaust gas flowing into the filter 23 and the amount of exhaust gas flowing into the bypass passage 65 in the exhaust pipe 20 in a region where the bypass passage 65 branches from the exhaust pipe 20. 66 is arranged. A step motor 67 is connected to the flow rate control valve 66. The step motor 67 is connected to the output port 36 via the corresponding drive circuit 38. The step motor 67 causes the flow rate control valve 66 to move to the position shown in FIG.
It is possible to continuously position between the position shown in FIG.

Further, a reducing agent injection valve 68 capable of injecting a reducing agent (for example, hydrocarbon) is attached immediately upstream of the filter 23. The reducing agent injection valve 68 is connected to the output port 36 via the corresponding drive circuit 38, and its operation is controlled by the electronic control unit 30.

Now, when no special control for maintaining or recovering the performance of the filter 23 is required, that is, normally, the flow rate control valve 66 is arranged as shown in FIG.
It is positioned at the position shown in. At this time, all the exhaust gas flows into the filter 23, and the fine particles in the exhaust gas are collected by the filter 23 and oxidized and removed.

On the other hand, when a special control for maintaining or recovering the performance of the filter 23 is required, that is, when a certain amount or more of fine particles are accumulated in the filter 23, the flow rate control valve 66. Is the position shown in FIG. 10 (B) and, in some cases, the position shown in FIG.
It is positioned at any position between the positions shown in 0 (B). At this time, most of the exhaust gas flows into the bypass passage 65, and the remaining exhaust gas flows into the filter 23. While the exhaust gas is flowing into the bypass passage 65, the fine particles in the exhaust gas that have passed through the bypass passage 65 are collected by the sweeper 45 and are oxidized and removed. Then, while the exhaust gas is being bypassed, the amount of fine particles flowing into the filter 23 is small, and therefore, the oxidizable and removable amount of the filter 23 is larger than the amount of fine particles flowing into the filter 23. Therefore, the fine particles deposited on the filter 23 are completely oxidized and removed while the exhaust gas is bypassed.

Further, even if the exhaust gas is bypassed, it is impossible to completely oxidize and remove the fine particles deposited on the filter 23, or while the exhaust gas is bypassed, the filter 23 is removed within a predetermined period. When it is not possible to completely oxidize and remove the particulates deposited on the filter 23, the reducing agent is injected from the reducing agent injection valve 68 to the filter 23 so as to promote the oxidative removal of the particulates in the filter 23.

Thus, according to the second embodiment, as in the first embodiment, by disposing the sweeper 45 downstream of the filter 23, the exhaust purification can be performed without significantly increasing the pressure loss of the entire exhaust purification system. The particulate removal rate of the entire device is improved.

[0095]

According to the present invention, while the performance of the particulate filter is maintained or restored by the performance maintaining / restoring means, the amount of fine particles in the exhaust gas downstream of the particulate filter is increased. Even if
Since such particles are captured by the sweeper, deterioration of exhaust emission is suppressed. Further, since the opening of the exhaust flow passage of the sweeper of the present invention is partially but closed, at least a part of the exhaust gas will pass through the pores of the partition wall, and therefore the fine particles of the sweeper of the present invention will be obtained. The collection rate is relatively high, and in this respect also, according to the present invention, deterioration of exhaust emission is suppressed. Further, in the sweeper of the present invention, since the partition walls of the portion that closes the opening of the exhaust flow passage are inclined so as to approach each other, the exhaust resistance is increased by disposing the sweeper downstream of the particulate filter. Suppressed. Further, the sweeper of the present invention is provided with a small hole having a flow passage cross-sectional area smaller than the flow passage cross-sectional area of the exhaust flow passage and larger than the flow passage cross-sectional area of the pores of the partition wall, and the exhaust gas is filled with the small pores. Also in this respect, according to the present invention, an increase in exhaust resistance due to the placement of the sweeper downstream of the particulate filter is suppressed in this respect as well.

[Brief description of drawings]

FIG. 1 is an overall view of an internal combustion engine equipped with an exhaust emission control device of the present invention.

FIG. 2 is a diagram showing an exhaust emission control device of a first embodiment.

FIG. 3 is a diagram showing a particulate filter in detail.

FIG. 4 is a diagram showing a sweeper in detail.

FIG. 5 is a diagram for explaining flow characteristics in a conventional sweeper.

FIG. 6 is a diagram for explaining flow characteristics in the sweeper of the present invention.

FIG. 7 is a diagram for explaining the function of oxidizing and removing fine particles in the particulate filter and the sweeper of the present invention.

FIG. 8 is a diagram for explaining a particulate particle deposition action in the particulate filter and the sweeper of the present invention.

FIG. 9 is a view showing the amount of fine particles that can be removed by oxidation in the particulate filter and the sweeper of the present invention.

FIG. 10 is a diagram showing an exhaust emission control device of a second embodiment.

[Explanation of symbols]

1 ... Engine body 22 ... Exhaust gas purification device 23 ... Particulate filter 20a ... first exhaust branch pipe 20b ... second exhaust branch pipe 43 ... Switching valve 45 ... Sweeper 52, 53 ... Tapered wall 54, 59 ... Partition walls 55, 56 ... Small holes 57, 58 ... Exhaust flow passage 60 ... Platinum 61 ... Active oxygen generator 65 ... Bypass passage 66 ... Flow rate switching valve 68 ... Reducing agent injection valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01D 53/94 F01N 3/08 A F01N 3/08 B 3/28 301C 3/28 301 7/08 B 7 / 08 B01D 46/00 F // B01D 46/00 53/36 103C 103B (72) Inventor Kazuhiro Ito 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Town 1 Toyota Motor Corporation (72) Inventor Takamitsu Asanuma Toyota City, Aichi Prefecture Toyota Town No. 1 Toyota Motor Co., Ltd. (72) Inventor Koichi Kimura No. 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Shunsuke Toshioka No. 1 Toyota Town, Aichi Prefecture Toyota Motor Vehicle Co., Ltd. (72) Inventor Akira Akira Prefecture, Toyota City, Aichi Prefecture 1 Toyota Town F-Term (Reference) 3G004 AA01 BA06 CA03 DA24 E A01 3G090 AA03 AA04 BA01 CB04 CB24 DA18 DA20 3G091 AA01 AA11 AA18 AB06 AB08 AB13 BA07 BA16 CA18 DA02 EA01 EA07 FC01 GA06 GB02Y GB03Y GB04Y GB06W HA05 HA07 HBB03 BA14 BA01 BA14 BA01 BA14 BA12 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 BA02 AC02 BA02 CC26 CD05 CD08 CD10 DA01 DA03 DA05 DA08 DA10 EA04 4D058 JA32 JB22 KB11 MA44 QA01 QA03 QA19 QA23 SA08 TA06

Claims (8)

[Claims] 1. A particulate filter for collecting particulates in exhaust gas, and a performance maintaining / maintaining function for maintaining or restoring the performance of the particulate filter.
An exhaust gas purification device comprising a recovery means for maintaining the performance of the particulate filter by the performance maintaining / restoring means or increasing the amount of fine particles in the exhaust gas downstream of the particulate filter while the performance is being recovered. In the above, the exhaust gas that is provided downstream of the particulate filter is equipped with a sweeper capable of collecting fine particles in the exhaust gas, and the sweeper extends from upstream to downstream defined by a plurality of partition walls extending from upstream to downstream thereof. At least one of the exhaust flow passages of the sweeper having a flow passage, the partition wall of the sweeper being formed of a porous material having pores.
The partition walls that define at least one of the upstream end and the downstream end of the two exhaust flow passages are inclined so as to approach each other, and the slanted partition walls define small holes at the upstream end or the downstream end of the exhaust flow passage. The exhaust passage is partially closed at its upstream end or downstream end, and the passage cross-sectional area of the small hole defined by the slanted partition wall is the passage cutoff of the exhaust passage of the sweeper. An exhaust gas purification device characterized by being smaller than the area and larger than the flow passage cross-sectional area of the pores of the partition wall. 2. The exhaust emission control device according to claim 1, wherein the small hole is defined by a partition wall that is slanted by bending and deforming the upstream end or the downstream end of the partition wall to gather them together. . 3. The active oxygen is trapped in the form of active oxygen when the particulate filter traps ambient oxygen when excess oxygen is present in the ambient and releases ambient oxygen when the ambient oxygen concentration decreases. 2. The active oxygen generating agent to be generated is carried, and the fine particles trapped in the particulate filter are continuously oxidized and removed by the active oxygen generated by the active oxygen generating agent. Exhaust gas purification device described. 4. A releases the NO _x which the particulate the filter active oxygen generating agent carried on there is an excess of oxygen in the ambient to capture NO _x and oxygen concentration around is captured and reduced N that can be reduced and purified
The exhaust emission control device according to claim 3, which has an O _x reduction purification capability. 5. A particulate filter further comprises an exhaust flow reversal mechanism for reversing an exhaust gas inflow side into which exhaust gas flows and an exhaust gas outflow side from which exhaust gas flows out, and the performance maintaining / restoring means comprises the above exhaust gas. The performance of the particulate filter is maintained or restored by reversing the exhaust gas inflow side and the exhaust gas outflow side in the particulate filter by the flow reversing mechanism. Exhaust gas purification device described. 6. A bypass passage for bypassing the particulate filter to the exhaust gas, and the exhaust gas, which normally allows almost all of the exhaust gas to flow into the particulate filter. The performance maintaining / restoring means further comprises a flow rate control valve capable of adjusting the amount of exhaust gas flowing into the bypass passage, and a reducing agent injection means for injecting the reducing agent into the particulate filter. At least a part of the exhaust gas is caused to flow into the bypass passage by the flow rate control valve, and the reducing agent is injected from the reducing agent injection means to supply the reducing agent to the particulate filter, thereby collecting the particulate filter. The performance of the particulate filter is maintained by accelerating the oxidation of the particulates. The exhaust gas purification device according to any one of claims 1 to 4, wherein the exhaust gas purification device is held or recovered. 7. The sweeper generates active oxygen by trapping ambient oxygen when excess oxygen exists in the surroundings and releasing trapped oxygen in the form of active oxygen when the ambient oxygen concentration decreases. 7. The active oxygen generator is carried, and the fine particles collected by the sweeper are continuously oxidized and removed by the active oxygen generated by the active oxygen generator. The exhaust emission control device according to one. 8. release the NO _x entrapping the oxygen concentration around and capture the NO _x when the active oxygen generating agent, which is supported on the sweeper exists excess oxygen in the ambient is reduced reduction purification The exhaust emission control device according to claim 7, which has a NO _x reduction purification capability that can be achieved.