JP3959611B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust emission control device that is provided in an exhaust system of an internal combustion engine (hereinafter referred to as an engine) and includes a particulate filter that collects particulate matter (hereinafter abbreviated as PM) in exhaust gas. is there.
[0002]
[Related background]
Exhaust gas discharged from a diesel engine or the like contains a large amount of PM in addition to HC, CO, NOx and the like, and a particulate filter has been proposed as a post-processing device for processing this PM. The filter is configured as a so-called wall flow type in which the upstream and downstream openings of a large number of passages along the flow direction of the exhaust gas are alternately closed, and the exhaust gas is circulated through a porous partition wall forming the passage. The PM in the exhaust gas is collected when circulating through the partition wall.
[0003]
[Problems to be solved by the invention]
The PM deposited on the filter is incinerated and removed by spontaneous ignition when the exhaust gas is in an operating state where the exhaust temperature is high. However, the operation state in which continuous regeneration by the natural ignition cannot be obtained continues, and PM is deposited on the filter. The amount may increase gradually. In such a case, the wall flow filter described above is directly connected to clogging of the partition wall, and normal engine operation cannot be maintained due to a sudden increase in exhaust resistance.
[0004]
Therefore, it is necessary to perform a forced regeneration process for forcibly removing the accumulated PM by incineration when the accumulated amount of PM exceeds an allowable value. The forced regeneration process includes, for example, post injection for injecting additional fuel in the expansion stroke or exhaust stroke, or supply of unburned fuel from unburned fuel supply means provided in the exhaust system, and the supplied fuel is burned. Although the temperature of the filter is raised, there is an adverse effect that the amount of fuel consumption increases due to the implementation of the forced regeneration process and the configuration of the exhaust gas purification apparatus becomes complicated.
[0005]
An object of the present invention is to provide an exhaust emission control device for an internal combustion engine that can reliably reduce the PM emission amount without causing clogging while avoiding the harmful effects caused by the forced regeneration process.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is a flow-through type trap device provided in an exhaust system of an internal combustion engine and having a plurality of passages along a flow direction of exhaust gas formed by a plurality of partition walls; It is provided upstream of the trap device of the exhaust system, and includes a swirl flow imparting means for imparting a swirl flow to the exhaust gas, and the trap device carries a metal having an oxidizing function.
[0007]
Accordingly, the exhaust gas discharged from the internal combustion engine generates a swirling flow by the swirling flow applying means, flows at an angle with respect to the inlet of each passage of the downstream trap means, and collides with a partition wall forming the passage. Soot, which is one of the main components of PM (particulate matter), adheres to the partition wall when the exhaust gas collides with the partition wall, so that the soot in the exhaust gas is sequentially collected by the trap device.
[0008]
In the high load region of the internal combustion engine, the trap device is sufficiently heated as the exhaust gas temperature rises. Therefore, NO ₂ generated from NO in the exhaust gas by using the oxidation function of the trap device is used as an oxidant. Alternatively, oxidation by oxygen is promoted by the catalytic function of the trap device, and soot deposited on the trap device is continuously burned and removed (continuous regeneration). Although the ratio of soot in PM increases in a high load region, soot is quickly incinerated and removed, and as a result, the amount of PM emission is reliably reduced.
[0009]
On the other hand, in the low load region of the internal combustion engine, although the SOF (soluble organic component) in the PM is purified by the oxidation function of the trap device, the exhaust temperature is low, so the soot deposited on the trap device cannot be incinerated and removed. . However, the amount of soot generated is small in the low load range, and the entire PM emission amount is reliably reduced by purifying the SOF that occupies a large proportion of the PM.
[0010]
For example, when the operation in a low load region is continued and the above-described continuous regeneration action cannot be obtained, the amount of soot accumulated in the trap device gradually increases, but the accumulated soot hinders the flow of exhaust gas. Then, under the pressure of the exhaust gas, the soot is appropriately separated from the partition wall and discharged downstream. Therefore, there is no possibility that the trap device is clogged with the accumulated soot, and it is not necessary to perform a forced regeneration process for preventing clogging.
[0011]
According to a second aspect of the present invention, there is provided a flow-through trap device provided in an exhaust system of an internal combustion engine and having a plurality of passages along a flow direction of exhaust gas formed by a plurality of partition walls, and upstream of the trap device of the exhaust system. Provided with a swirling flow imparting means for imparting a swirling flow to the exhaust gas, and an oxidation catalyst provided upstream of the swirling flow imparting means of the exhaust system.
In the present invention, instead of the oxidation function of the trap device of the first aspect of the invention, the upstream oxidation catalyst performs the same function, purifies SOF in the low load region, and continuously regenerates the trap device in the high load region. Necessary NO ₂ is generated from NO in the exhaust gas. Therefore, as described in claim 1, the purification of SOF is mainly performed in the low load region, and the continuous regeneration action is mainly performed on the soot in the high load region, and the total PM emission amount can be reliably reduced, and When the continuous regeneration action cannot be obtained, the soot accumulated in the trap device is appropriately discharged to the downstream side, so that the forced regeneration process for preventing the trap device from being clogged becomes unnecessary.
[0012]
According to a third aspect of the present invention, there is provided a flow-through type trap device provided in an exhaust system of an internal combustion engine, having a plurality of passages along a flow direction of exhaust gas formed by a plurality of partition walls, and upstream of the exhaust system trap device. Provided with a swirl flow imparting means for imparting a swirl flow to the exhaust gas and an oxidation catalyst provided upstream of the swirl flow imparting means of the exhaust system, wherein the trap device carries a metal having an oxidation function It is.
[0013]
In the present invention, in addition to the oxidation function of the trap device of the first aspect of the invention, the upstream oxidation catalyst performs the same function, purifies SOF in the low load region, and NO required for continuous regeneration in the high load region. ₂ is produced from NO in the exhaust gas. Therefore, as described in claim 1, the purification of SOF is mainly performed in the low load region, and the continuous regeneration action is mainly performed on the soot in the high load region, and the total PM emission amount can be reliably reduced, and When the continuous regeneration action cannot be obtained, the soot accumulated in the trap device is appropriately discharged to the downstream side, so that the forced regeneration process for preventing the trap device from being clogged becomes unnecessary.
[0014]
According to a fourth aspect of the present invention, the passage sectional area of the trap device is formed smaller than the passage sectional area of the swirling flow applying means.
Therefore, when the exhaust gas accompanied by the swirling flow from the swirling flow applying means approaches the trap device, the flow velocity of the exhaust gas is increased as the passage cross-sectional area is reduced. As a result, the exhaust gas collides more strongly against the partition wall of the trap device, and PM adheres more firmly to the partition wall.
[0015]
According to a fifth aspect of the present invention, the trap device has a NOx selective reduction function, and supplies the reducing agent to the exhaust system upstream of the swirling flow applying means.
For example, HC or the like contained in the fuel is used as the reducing agent, and the fuel supplied to the exhaust system functions as a reducing agent to reduce NOx in the exhaust gas on the trap device, thereby achieving NOx reduction. The Moreover, since the reducing agent at this time is supplied onto the trap device in a state of being uniformly dispersed by the swirling flow generated by the swirling flow applying means, the maximum NOx reduction effect can be obtained by effectively using the reducing agent. It is done.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in an exhaust emission control device for a common rail diesel engine will be described.
FIG. 1 is an overall configuration diagram illustrating an exhaust emission control device for a diesel engine according to a first embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. The exhaust purification device 1 is provided in the exhaust passage 3 of the engine 2, and although not shown, a silencer is provided on the downstream side of the exhaust purification device 1. The exhaust emission control device 1 is composed of an upstream swirling flow imparting portion 4 (swirl flow imparting means) and a downstream diesel particulate filter 5 (a trap device, hereinafter abbreviated as DPF). 4 and 5 are accommodated in a cylindrical casing 6.
[0017]
The inside of the casing 6 is divided into an upstream side and a downstream side by a partition wall 7 of the swirl flow imparting unit 4. Hereinafter, an upstream space of the partition wall 7 is referred to as an upstream space 8 a and a downstream space is referred to as a downstream space 8 b. The wind guide pipes 9 are respectively penetrated at two positions on the partition wall 7 centering on the axis L of the casing 6 at 180 °, and these wind guide pipes 9 are welded and fixed at right angles to the partition wall 7. Yes.
[0018]
Both the air guide pipes 9 extend toward the downstream space 8b and are curved so that the opening ends thereof are directed in the same circumferential direction (counterclockwise as shown in FIG. 2) about the axis L. Yes. The number and shape of the air guide pipes 9 can be arbitrarily changed. For example, three air guide pipes 9 may be arranged at intervals of 120 ° with the axis L as the center.
On the other hand, the DPF 5 is made of, for example, a monolithic cordierite carrier, and has a large number of passages 11 along the longitudinal direction of the exhaust gas by the partition wall 10. Each passage 11 has a honeycomb-like or lattice-like cross section, and the DPF 5 functions as a so-called flow-through type honeycomb through which exhaust gas flows along each passage 11. On the surface of the DPF 5, a catalyst mainly composed of a noble metal such as platinum (Pt) or palladium (Pd) is supported. As will be described later, the DPF 5 collects PM, but since PM accumulation is concentrated near the entrance of the passage 11, it is not necessary to be as long as a general wall flow DPF or an oxidation catalyst carrier. Its total length is set fairly short.
[0019]
In the exhaust emission control device 1 configured as described above, exhaust gas discharged from the engine 2 during operation is introduced into the upstream space 8 a in the casing 6 through the exhaust passage 3. The introduced exhaust gas is guided to the downstream space 8b through the air guide pipe 9, but the opening end of the air guide pipe 9 is eccentric with respect to the axis L and is directed in the same circumferential direction. The exhaust gas discharged from the wind guide pipe 9 causes a counterclockwise swirling flow around the axis L in the downstream space 8b as indicated by an arrow in the figure.
[0020]
Therefore, the exhaust gas in the downstream space 8b flows at an angle with respect to the entrance of each passage 11 of the DPF 5, collides with the partition wall 10 forming the passage 11, and thereafter flows through each passage 11 and then from the casing 6 It is exhausted and exhausted to the atmosphere through a silencer.
Next, the PM purification action by the exhaust gas purification device 1 of the diesel engine 2 configured as described above will be described.
[0021]
As is well known, the PM contained in the exhaust gas is mainly composed of three types of fuel, SOF composed of unburned fuel and oil, soot composed of carbon, etc., and sulfate generated by the oxidation action of the catalyst. PM emissions are evaluated. Here, it has been confirmed that the generation state of SOF and soot changes according to the load region of the engine 2, and the SOF rate increases in the low load region and the soot rate increases in the high load region.
[0022]
In general, PM is present in a state where SOF is attached to the surface of soot particles, as enlargedly displayed in FIG. Here, when the exhaust gas collides at an angle with the entrance of the partition wall 10 of the DPF 5 by the swirling flow as described above, the PM in the exhaust gas adheres to the partition wall 10, and thereby the PM in the exhaust gas is sequentially collected by the DPF 5. The
Since the exhaust gas temperature is low in the low load region of the engine 2, a continuous regeneration action to be described below for incinerating and removing the soot cannot be obtained, so that the purification action for the soot is hardly exhibited. On the other hand, SOF is purified by the oxidation function of DPF 5 from a temperature lower than the soot oxidation. Therefore, the entire PM emission amount is reliably reduced by purifying SOF which occupies a large proportion of PM.
[0023]
Further, in the high load range, the SPF purification action by the oxidation function of the DPF 5 is exhibited as in the low load range, and the DPF 5 is sufficiently heated as the exhaust temperature of the engine 2 rises. The continuous regeneration action similar to that of a general wall flow type DPF is achieved. That is, NO ₂ is generated from NO in the exhaust gas by the oxidation function of DPF 5, and the soot deposited on DPF 5 burns using this NO ₂ as an oxidizing agent. Further, the soot oxidation by oxygen is promoted by the oxidation promoting action by the catalyst on the DPF 5. Soot has already been collected on the DPF 5 in the low load region, and the proportion of soot in the PM increases with the shift to the high load region, but these soot is quickly incinerated and removed, and Since the SOF is also purified by the oxidation function as in the low load region, the PM emission amount is reliably reduced as a result.
[0024]
For example, when the operation in the low load region is continued and the above-described continuous regeneration action cannot be obtained, the soot accumulation amount in the DPF 5 gradually increases as in the wall flow type DPF, but the flow through of the present embodiment In the formula DPF5, when the accumulation amount of soot increases and the flow of exhaust gas is hindered, the soot is appropriately peeled from the partition wall 10 and discharged downstream by receiving the pressure of the exhaust gas. There is no risk of clogging. Therefore, it is not necessary to perform the forced regeneration process for preventing the clogging of the DPF 5, and adverse effects caused by the execution of the process, for example, an increase in fuel consumption and a complicated configuration can be avoided.
[0025]
The soot discharge leads to an increase in the PM emission amount. However, if the accumulation amount of the soot in the DPF 5 decreases and the exhaust gas smoothly circulates, the soot separation is interrupted by itself, so The amount of soot to be performed becomes the minimum necessary, and is slightly suppressed as compared with the generation amount of the entire PM. Therefore, the total PM emission amount can be sufficiently suppressed.
[0026]
[Second Embodiment]
Next, a second embodiment in which the present invention is embodied in another exhaust purification device for a common rail type diesel engine will be described. The present embodiment is different from the first embodiment in that an oxidation catalyst 21 is added on the upstream side of the swirling flow imparting section 4 of the exhaust purification device 1, and the other configurations are the same. . Therefore, description of the part of the same structure is abbreviate | omitted, and demonstrates a different point mainly.
[0027]
FIG. 4 is an overall configuration diagram showing the exhaust gas purification apparatus for a diesel engine according to the second embodiment. As shown in this figure, the upstream space 8 a in the casing 6 of the exhaust gas purification apparatus 1, that is, upstream from the swirl flow imparting unit 4. An oxidation catalyst 21 is installed on the side. The configuration of the oxidation catalyst 21 is the same as that of a general oxidation catalyst. For example, a catalyst mainly containing a noble metal such as Pt or Pd is supported on the surface of a cordierite carrier.
[0028]
In the exhaust emission control device 1 configured as described above, the SOF purification is mainly performed in the low load region as in the first embodiment, and the continuous regeneration operation is mainly performed on the soot in the high load region, and the continuous regeneration operation is performed. When it cannot be obtained, the soot accumulated in the DPF 5 is appropriately discharged to the downstream side, so that a forced regeneration process for preventing clogging of the DPF 5 can be made unnecessary. In addition, the upstream side oxidation catalyst 21 plays a role of assisting the oxidizing action of the DPF 5, purifies SOF in the low load region, and generates NO ₂ necessary for continuous regeneration from the NO in the exhaust gas in the high load region. Therefore, the PM emission amount can be further reduced as compared with the first embodiment.
[0029]
Further, the NO ₂ generated in the upstream side oxidation catalyst 21 is supplied onto the DPF 5 in a state of being uniformly dispersed by the swirling flow generated by the swirling flow imparting section 4, so that the unburned soot remains on the DPF 5. There is also an advantage that the DPF 5 can be regenerated more reliably.
If the oxidation catalyst 21 is provided on the upstream side in this way, the oxidation function of the DPF 5 is not essential. Therefore, the catalyst may not be supported on the DPF 5, and the cordierite carrier having the PM collecting function may be used as it is. Even in this case, the upstream side oxidation catalyst 21 performs the SOF purification action in the low load area and the NO ₂ generation action in the high load area, so that the PM emission amount can be sufficiently reduced. Can do.
[0030]
[Third Embodiment]
Next, a third embodiment in which the present invention is embodied in another exhaust purification device for a common rail type diesel engine will be described. The present embodiment is different from the first embodiment in that the shape of the casing 6 is changed in order to increase the flow rate of exhaust gas, and the NOx reduction function is added to the DPF 5. The configuration is the same. Therefore, description of the part of the same structure is abbreviate | omitted, and demonstrates a different point mainly.
[0031]
FIG. 5 is a cross-sectional view showing a swirl flow imparting portion of the exhaust purification device for a diesel engine according to the third embodiment. In the exhaust purification apparatus of this embodiment, the casing 6 has a reduced diameter between the swirl flow imparting unit 4 and the DPF 5, and as a result, the passage cut-off on the DPF 5 side with respect to the cross-sectional area on the swirl flow imparting unit 4 side The area is set small.
In addition to the oxidation catalyst, the DPF 5 carries a selective reduction type NOx catalyst such as Cu / ZSM5. On the other hand, unburned fuel can be arbitrarily supplied to the exhaust passage 3 of the engine 2. Yes. Specifically, for example, light oil is injected from an injection valve provided in the exhaust passage 3, or additional fuel is injected in the expansion stroke or exhaust stroke of the engine 2 to supply the exhaust passage 3 with unburned fuel. A method of performing injection can be considered.
[0032]
The exhaust emission control device 1 configured as described above exhibits the following operations in addition to the operations described in the first embodiment. First, when the exhaust gas accompanied by the swirling flow from the swirling flow imparting unit 4 approaches the DPF 5, the angular momentum is preserved as the case outer diameter is reduced, so that a phenomenon occurs in which the swirling flow velocity of the exhaust gas is increased. Accordingly, the exhaust gas collides with the partition wall 10 of the DPF 5 more strongly, so that PM can be adhered more firmly to the partition wall 10 and the PM collection function of the DPF 5 can be strengthened.
[0033]
Further, in an operating state where the engine 2 has a large amount of NOx emission, unburned fuel is supplied to the exhaust passage 3 by operating the injection valve or performing post injection. Since the HC in the supplied unburned fuel functions as a reducing agent on the NOx catalyst and reduces NOx in the exhaust gas, there is also an advantage that NOx which is a problem particularly in a diesel engine can be efficiently reduced.
[0034]
Moreover, since the supplied unburned fuel is supplied onto the DPF 5 in a state of being uniformly dispersed by the swirl flow generated by the swirl flow imparting unit 4, the maximum NOx reduction effect is obtained by effectively using HC. be able to. Here, as a configuration of the apparatus, the oxidation catalyst 21 may be provided on the upstream side of the swirling flow imparting unit 4 as in the first and second embodiments. In this case, the position where the reducing agent is supplied is intermediate between the oxidation catalyst 21 and the swirl flow imparting unit 4.
[0035]
On the other hand, the configuration of the swirl flow imparting unit 4 can be variously changed. Hereinafter, modifications thereof will be described as fourth to sixth embodiments. In addition, since parts other than the swirl | flow flow provision part 4 are the same as that of the said 1st Embodiment, a different point is demonstrated mainly.
[Fourth Embodiment]
FIG. 6 is a cross-sectional view showing a swirl flow imparting portion of the exhaust purification system for a diesel engine according to the fourth embodiment, and FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. As shown in these drawings, the partition wall 31 of the swirling flow imparting section 4 is press-molded, and air guide holes 32 are integrally formed at two positions opposed to each other by 180 ° centering on the axis L of the casing 6. . These air guide holes 32 open in the same circumferential direction (counterclockwise) around the axis L in the downstream space 8b, and have the same effect as the air guide pipe 9 of the first embodiment.
[0036]
That is, when the exhaust gas in the upstream space 8a is released from the air guide hole 32 into the downstream space 8b, a swirling flow is generated. Therefore, the exhaust gas collides with the partition wall 10 of the DPF 5, and the PM in the exhaust gas enters the DPF 5. As a result, the same purification action as in the first embodiment can be obtained.
[Fifth Embodiment]
FIG. 8 is a cross-sectional view showing a swirl flow imparting portion of an exhaust gas purification apparatus for a diesel engine according to a fifth embodiment, and FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. As shown in these drawings, a center pipe 41 is disposed on the axis L in the casing 6, and an air guide plate 42 is disposed so as to form a spiral shape in the direction of the axis L around the center pipe 41. ing.
[0037]
Accordingly, the exhaust gas in the upstream space 8a is discharged into the downstream space 8b while being spirally guided by the air guide plate 42 to generate a swirling flow, whereby PM in the exhaust gas is collected in the DPF 5.
[Sixth Embodiment]
FIG. 10 is a cross-sectional view showing a swirl flow imparting portion of the exhaust purification system for a diesel engine according to the sixth embodiment, and FIG. 11 is a cross-sectional view taken along the line XI-XI of FIG. As shown in these drawings, a center pipe 51 is disposed on the axis L in the casing 6, and four air guide plates 52 are disposed around the center pipe 51. Each air guide plate 52 is twisted in the same direction, thereby forming a fan shape as a whole.
[0038]
This wind guide plate 52 has the same effect as the wind guide plate 42 of the fourth embodiment, and generates a swirling flow in the downstream space 8b while guiding the exhaust gas in a spiral shape, thereby causing PM in the exhaust gas to flow into the DPF 5. Collect.
This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in each of the above embodiments, the exhaust gas purification device for a common rail type diesel engine is embodied. However, the type of the engine 2 is not limited to this, and for example, it is embodied as an exhaust gas purification device for a normal diesel engine. May be.
[0039]
【The invention's effect】
As described above, according to the exhaust gas purification apparatus for an internal combustion engine of the first to third aspects of the present invention, it is possible to reliably reduce the PM emission amount without causing clogging while avoiding the harmful effects caused by the forced regeneration process. can do.
According to the exhaust emission control device for an internal combustion engine of the fourth aspect of the invention, in addition to the first to third aspects of the invention, PM is more firmly attached to the partition wall of the trap device, and the PM trap of the trap device is collected. Function can be strengthened.
[0040]
According to the exhaust emission control device for an internal combustion engine of the fifth aspect of the invention, in addition to the first to fourth aspects of the invention, NOx in the exhaust gas can be reduced on the trap device to obtain a NOx reduction effect.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an exhaust emission control device for a diesel engine according to a first embodiment.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a partial enlarged cross-sectional view showing a state of PM deposition on the DPF.
FIG. 4 is an overall configuration diagram showing an exhaust emission control device for a diesel engine according to a second embodiment.
FIG. 5 is a cross-sectional view showing a swirl flow imparting portion of an exhaust emission control device for a diesel engine according to a third embodiment.
FIG. 6 is a cross-sectional view showing a swirl flow imparting portion of an exhaust emission control device for a diesel engine according to a fourth embodiment.
7 is a cross-sectional view taken along line VII-VII in FIG. 6 showing details of the swirl flow imparting portion.
FIG. 8 is a cross-sectional view showing a swirl flow imparting portion of an exhaust gas purification apparatus for a diesel engine according to a fifth embodiment.
9 is a cross-sectional view taken along the line IX-IX of FIG. 8 showing details of the swirl flow imparting portion.
FIG. 10 is a cross-sectional view showing a swirl flow imparting portion of an exhaust emission control device for a diesel engine according to a sixth embodiment.
11 is a cross-sectional view taken along the line XI-XI in FIG. 10 showing details of the swirl flow imparting section.
[Explanation of symbols]
2 Engine (Internal combustion engine)
3 Exhaust passage 4 Swirl flow imparting section (swirl flow imparting means)
5 DPF (trap device)
10 partition wall 11 passage 21 oxidation catalyst

Claims (5)

A flow-through type trap device provided in an exhaust system of an internal combustion engine and having a plurality of passages along a flow direction of exhaust gas formed by a plurality of partition walls;
A swirl flow imparting means provided upstream of the trap device of the exhaust system and imparting a swirl flow to the exhaust gas;
An exhaust gas purification apparatus for an internal combustion engine, wherein the trap device carries a metal having an oxidation function. A flow-through type trap device provided in an exhaust system of an internal combustion engine and having a plurality of passages along a flow direction of exhaust gas formed by a plurality of partition walls;
A swirl flow imparting means provided upstream of the trap device of the exhaust system and imparting a swirl flow to the exhaust gas;
An exhaust gas purification apparatus for an internal combustion engine, comprising: an oxidation catalyst provided upstream of the swirl flow imparting means of the exhaust system. A flow-through type trap device provided in an exhaust system of an internal combustion engine and having a plurality of passages along a flow direction of exhaust gas formed by a plurality of partition walls;
A swirl flow imparting means provided upstream of the trap device of the exhaust system and imparting a swirl flow to the exhaust gas;
An oxidation catalyst provided upstream of the swirl flow imparting means of the exhaust system,
An exhaust gas purification apparatus for an internal combustion engine, wherein the trap device carries a metal having an oxidation function.   The exhaust purification device for an internal combustion engine according to any one of claims 1 to 3, wherein the trap device has a passage cross-sectional area smaller than a passage cross-sectional area of the swirling flow applying means.   The exhaust gas purification of an internal combustion engine according to any one of claims 1 to 4, wherein the trap device has a NOx selective reduction function and supplies a reducing agent to an exhaust system upstream of the swirl flow applying means. apparatus.

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