JP6826058B2 - Exhaust gas purification device - Google Patents

Description

The present disclosure relates to an exhaust gas purification device.

An exhaust gas purification device is installed in the exhaust gas flow path of the internal combustion engine for the purpose of complying with the regulations regarding the exhaust gas component of the internal combustion engine. For the exhaust gas purification device, if it is a diesel engine, for example, an exhaust gas purification member such as a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a catalyst for selective catalytic reduction (SCR) is used in combination.

Among these exhaust gas purification members, the SCR catalyst (hereinafter, also referred to as “reduction catalyst”) is generally installed downstream of another catalyst or filter. SCR is a method of reducing NOx in exhaust gas with a reducing agent and a reducing catalyst to reform it into harmless nitrogen.

In SCR, in order to make the reducing catalyst function efficiently and improve the purification rate of the exhaust gas, the reducing agent is mixed and uniformly dispersed in the exhaust gas, and the exhaust gas containing the reducing agent is evenly distributed. It is necessary to bring it into contact with the reducing catalyst.

As a method of dispersing the reducing agent in the exhaust gas, there is a method of arranging a diffusion plate in the flow path of the exhaust gas. However, if the diffusion plate is arranged in the flow path, there is a disadvantage that the pressure loss becomes high and the flow of the exhaust gas is biased.

Therefore, an exhaust gas purification device has been proposed in which a guide wall is provided in the flow path of the exhaust gas and the reducing agent is diffused by the swirling flow generated by the guide wall (see Patent Document 1). In this exhaust gas purification device, in order to guide the flow path to the guide wall, the upper part of the guide wall is closed with a plate, and an introduction hole is provided in this plate.

JP-A-2017-145717

According to the exhaust gas purification device of Patent Document 1, the reducing agent can be diffused by a swirling flow. However, it is necessary to make the introduction holes smaller in order to promote mixing. Therefore, the area of the gas flow path becomes small, and as a result, the pressure loss of the device becomes large.

One aspect of the present disclosure is an object of the present invention to provide an exhaust gas purification device capable of improving the exhaust gas purification efficiency while suppressing an increase in pressure loss.

One aspect of the present disclosure is an exhaust gas purification device for an internal combustion engine. The exhaust gas purification device includes an exhaust gas purification unit, a reduction unit, a reducing agent supply unit, an exhaust gas pipeline, and a swirling flow generation unit. The exhaust gas purification unit is configured to reform or collect environmental pollutants in the exhaust gas. The reducing unit is provided on the downstream side of the exhaust gas purification unit in the flow direction of the exhaust gas, and is configured to reduce the exhaust gas in the presence of a reducing agent. The reducing agent supply unit is configured to supply the reducing agent to the exhaust gas on the upstream side of the reducing unit in the flow direction of the exhaust gas. The exhaust gas pipeline communicates between the exhaust port of the exhaust gas purification unit and the introduction port of the reduction unit. The swirl flow generator is installed in the exhaust gas pipeline.

Further, the swirling flow generating portion includes a first shielding portion configured to shield a part of the flow in the central axis direction of the exhaust gas pipeline, and a second shielding portion arranged on the downstream side of the first shielding portion. And have. The second shielding portion includes an annular portion having an opening formed in the radial center of the exhaust gas pipeline and configured to shield the flow in the central axial direction on the radial outer side of the opening, and the first shielding portion from the annular portion. It has a side wall portion that extends to and partially surrounds the opening of the annular portion in the circumferential direction. The first shielding portion overlaps with the opening of the annular portion when viewed from the central axis direction, and has a central portion separated from the inner surface of the exhaust gas pipeline and a peripheral portion extending from the central portion to the inner peripheral surface of the exhaust gas pipeline. And a plurality of through holes provided in the peripheral portion. The peripheral edge portion is arranged so as to at least overlap the outer edge of the opening of the annular portion in the radial direction of the open portion not surrounded by the side wall portion when viewed from the central axis direction. The reducing agent supply unit injects the reducing agent toward the side wall portion.

According to such a configuration, first, the flow of the exhaust gas in the central axis direction (hereinafter, also referred to as “first direction”) of the exhaust gas pipeline is outside the side wall portion of the second shielding portion by the first shielding portion. Is guided to. The flow guided to the side wall is divided into two flows by the side wall and flows toward the opening of the annular portion. As a result, the flow path of the exhaust gas is extended, and two swirling flows in opposite directions having a swirling axis parallel to the first direction are generated. Therefore, the reducing agent sprayed toward the side wall portion is efficiently diffused. As a result, the evaporation of the reducing agent is promoted and the dispersibility is improved. Further, a part of the exhaust gas flow passes through the plurality of through holes of the first shielding portion and joins the two swirling flows. As a result, the reducing agent and the exhaust gas are effectively agitated.

In the above configuration, it is not necessary to provide an introduction hole in the plate that closes the flow path, and the flow path diameter can be adjusted to an arbitrary size by the first shielding portion. Therefore, it is possible to suppress an increase in pressure loss while increasing the purification efficiency of exhaust gas.

In one aspect of the present disclosure, the area of the region in the exhaust gas pipeline where the first shielding portion is not arranged may be larger than the total area of the plurality of through holes when viewed from the central axis direction. According to such a configuration, the above-mentioned two swirling flows can be generated more reliably. As a result, the purification efficiency of the exhaust gas can be improved.

In one aspect of the present disclosure, the length of the contact portion between the peripheral edge portion and the inner peripheral surface of the exhaust gas pipeline in the circumferential direction may be 1/2 or less of the inner peripheral length of the exhaust gas pipeline. .. According to such a configuration, it is possible to more reliably suppress the increase in pressure loss while increasing the purification efficiency of the exhaust gas.

In one aspect of the present disclosure, the first end portion in the circumferential direction of the side wall portion overlaps with the first end portion in the circumferential direction of the peripheral portion when viewed from the central axis direction, and the second end portion in the circumferential direction of the side wall portion is formed. , It may overlap with the second end portion in the circumferential direction of the peripheral portion when viewed from the central axis direction. According to such a configuration, the exhaust gas flowing from the upstream side surely collides with the side wall portion. As a result, the stirring performance can be ensured while reducing the pressure loss.

FIG. 1A is a schematic partial transmission perspective view of the exhaust gas purification device of the embodiment, and FIG. 1B is a schematic central sectional view of the exhaust gas purification device of FIG. 1A. 2A is a schematic perspective view of a swirling flow generating portion in the exhaust gas purification device of FIG. 1A, and FIG. 2B is a schematic plan view of a swirling flow generating portion of FIG. 2A. FIG. 3 is a schematic perspective view of the second shielding portion in the swirling flow generating portion of FIG. 2A. FIG. 4 is a schematic partial cross-sectional perspective view illustrating the flow of exhaust gas in the swirling flow generating portion of FIG. 2A.

Hereinafter, embodiments to which the present disclosure has been applied will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
The exhaust gas purification device (hereinafter, also simply referred to as “purification device”) 1 shown in FIGS. 1A and 1B is provided in the exhaust gas flow path of the internal combustion engine to reduce environmental pollutants in the exhaust gas. The purification device 1 includes an exhaust gas purification unit 2, a reduction unit 3, a reducing agent supply unit 4, an exhaust gas pipeline 5, and a swirling flow generation unit 6.

The internal combustion engine provided with the purification device 1 is not particularly limited, but the purification device 1 can be particularly preferably used as an exhaust gas purification device for a diesel engine. Examples of the diesel engine include those used for driving or power generation in transportation equipment such as automobiles, railways, ships, and construction machinery, and power generation facilities.

<Exhaust gas purification unit>
The exhaust gas purification unit 2 reforms or collects environmental pollutants in the exhaust gas. Here, the "environmental pollutant" means carbon monoxide (CO), nitrogen oxide (NOx), granular substance (PM), sulfur oxide (SOx), hydrocarbons (HC) and the like.

As shown in FIG. 1B, the exhaust gas purification unit 2 has a purification member 21 for purifying the exhaust gas and a tubular casing 22 in which the purification member 21 is housed. The exhaust gas flows along the central axis direction of the casing 22 while contacting the purification member 21 inside the casing 22.

Examples of the purification member 21 include a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a NOx adsorbent, and the like. DOC is a catalyst that oxidizes soluble organic components (SOF), CO and HC in PM contained in exhaust gas. The DPF is a filter that collects PM contained in the exhaust gas. The NOx adsorbent is a substance that adsorbs and removes NOx.

As the purification member 21, a tubular body having a honeycomb structure is generally used. When the exhaust gas passes through the inside of the honeycomb structure, the environmental pollutants in the exhaust gas are modified by the catalyst metal contained in the purification member 21 or captured by the purification member 21.

In FIGS. 1A and 1B, the exhaust gas purification unit 2 is arranged so that the flow direction of the exhaust gas inside is in the vertical direction, that is, the central axis of the tubular casing 22 is in the vertical direction. Further, the exhaust gas discharge port 2A of the exhaust gas purification unit 2 is formed so that the exhaust gas is discharged in the vertical direction. However, the flow direction of the exhaust gas in the exhaust gas purification unit 2 is not limited to the vertical direction, and may be a horizontal direction or a direction inclined with respect to the horizontal direction.

<Reduction section>
The reducing unit 3 reduces the exhaust gas in the presence of a reducing agent. Specifically, the reducing unit 3 reduces NOx in the exhaust gas with ammonia and a reduction catalyst, and reforms it into harmless nitrogen. Ammonia, which is a reducing agent, is generally produced by injecting urea water into an exhaust gas and hydrolyzing urea in the urea water.

The reduction unit 3 has a reduction catalyst 31 and a tubular casing 32 in which the reduction catalyst 31 is housed. The reduction catalyst 31 is composed of a base material such as ceramic and a metal catalyst supported on the base material. The exhaust gas flows along the central axis direction of the casing 32 while contacting the reduction catalyst 31 inside the casing 32.

The reduction unit 3 is connected to the downstream side of the exhaust gas purification unit 2 in the flow direction of the exhaust gas via the exhaust gas pipeline 5. The reduction unit 3 is arranged so that the flow direction of the exhaust gas inside is the same as that of the exhaust gas purification unit 2. That is, the central axis of the casing 32 of the reduction unit 3 is arranged in a direction that coincides with the central axis of the casing 22 of the exhaust gas purification unit 2.

<Reducing agent supply unit>
The reducing agent supply unit 4 supplies the reducing agent to the exhaust gas on the upstream side of the reducing agent 3 in the flow direction of the exhaust gas. In the present embodiment, as shown in FIGS. 1A and 1B, the reducing agent supply unit 4 is configured to inject the reducing agent into the exhaust gas pipeline 5.

Specifically, the reducing agent supply unit 4 has an injector that injects the reducing agent toward the side wall portion 8B of the second shielding portion 8 described later. This injector injects urea water, which is a reducing agent, from the peripheral surface of the exhaust gas pipeline 5 toward the central axis of the exhaust gas pipeline 5.

As the injector of the reducing agent supply unit 4, a known injector can be used. Further, in FIGS. 1A and 1B, only the connecting pipe to the exhaust gas pipeline 5 is shown as the reducing agent supply unit 4, and the members such as the injector are not shown.

<Exhaust gas pipeline>
The exhaust gas pipeline 5 is a pipe body that communicates the exhaust port 2A of the exhaust gas purification unit 2 and the introduction port 3A of the reduction unit 3. That is, the exhaust gas discharged from the exhaust gas purification unit 2 is introduced into the reduction unit 3 through the exhaust gas pipeline 5. A swirling flow generating portion 6 is arranged inside the exhaust gas pipeline 5. Further, a reducing agent supply unit 4 is connected to the peripheral surface of the exhaust gas pipeline 5.

The direction of the central axis of the exhaust gas pipeline 5 coincides with the direction of the central axis of the casing 22 of the exhaust gas purification unit 2 and the casing 32 of the reduction unit 3. That is, the exhaust gas pipeline 5 forms a straight exhaust gas flow path without bending between the exhaust gas purification unit 2 and the reduction unit 3.

In the present embodiment, the exhaust gas pipeline 5 is a straight pipe, and the exhaust port 2A of the exhaust gas purification unit 2 and the introduction port 3A of the reduction unit 3 have the same diameter. However, the exhaust port 2A of the exhaust gas purification unit 2 and the introduction port 3A of the reduction unit 3 do not necessarily have the same diameter.

<Swirl flow generator>
The swirling flow generating unit 6 is installed in the exhaust gas pipeline 5, and generates a plurality of swirling flows in the exhaust gas. As shown in FIGS. 2A and 2B, the swirling flow generating unit 6 has a first shielding unit 7 and a second shielding unit 8.

(1st shield)
The first shielding unit 7 shields a part of the flow in the first direction D1 which is the central axis direction of the exhaust gas pipeline 5 from the exhaust gas flowing in the exhaust gas pipeline 5.

As shown in FIG. 2A, the first shielding portion 7 has a central portion 7A, a peripheral portion 7B, and a plurality of through holes 7C. The first shielding portion 7 shields a part of the flow of the exhaust gas in the first direction D1 by the central portion 7A and the peripheral portion 7B.

The central portion 7A is a plate-shaped portion arranged in a direction in which the thickness direction coincides with the first direction D1. As shown in FIG. 2B, the central portion 7A is arranged at a position overlapping the opening 8C of the annular portion 8A described later when viewed from the central axis direction. Specifically, the central portion 7A covers the portion of the opening 8C of the annular portion 8A that does not overlap with the side wall portion 8B (that is, the portion that can be seen from the upstream side) from the upstream side. The central portion 7A is connected to the side wall portion 8B, while being arranged away from the inner surface of the exhaust gas pipeline 5. The portion of the space above the side wall portion 8B that is not covered (that is, does not overlap) with the central portion 7A constitutes the opening portion 7G.

The peripheral edge portion 7B is a portion extending in the radial direction from the outer edge of the central portion 7A to the inner peripheral surface of the exhaust gas pipeline 5. The peripheral edge portion 7B is arranged so as to at least overlap the outer edge of the opening 8C of the annular portion 8A in the radial direction of the open portion 8D not surrounded by the side wall portion 8B when viewed from the central axis direction. In the present embodiment, the peripheral edge portion 7B is partially overlapped with the side wall portion 8B when viewed from the central axis direction. The upstream surface of the peripheral edge 7B is flush with the upstream surface of the central 7A.

The first end 7D and the second end 7E of the peripheral portion 7B in the circumferential direction of the exhaust gas pipe 5 extend in the radial direction of the exhaust gas pipe 5, respectively. Further, the contact portion 7F of the peripheral portion 7B with the inner peripheral surface of the exhaust gas pipeline 5 extends to the downstream side (that is, the second shielding portion 8 side) along the first direction D1.

The length L of the peripheral portion 7B in the circumferential direction (that is, the length of the outer edge of the peripheral portion 7B) L is preferably ½ or less of the inner peripheral length of the exhaust gas pipeline 5. If the length L of the abutting portion is more than 1/2 of the inner peripheral length of the exhaust gas pipeline 5, the opening 7G (see FIG. 1B) of the first shielding portion 7 may become small and the pressure loss may increase. There is. Since the length L of the contact portion is 1/2 or less of the inner peripheral length of the exhaust gas pipeline 5, the region of the side wall portion 8B where the exhaust gas flowing from the upstream collides becomes wider, so that the stirring performance It is possible to reduce the pressure loss while ensuring the above.

The plurality of through holes 7C are provided in the peripheral edge portion 7B. The plurality of through holes 7C penetrate the peripheral edge portion 7B along the first direction D1. The plurality of through holes 7C are arranged radially outside the opening 8C when viewed from the central axis direction.

In the present embodiment, the plurality of through holes 7C are arranged at equal intervals on two arcs having different distances from the center of the exhaust gas pipeline 5. The plurality of through holes 7C can be formed by punching, for example. Further, the shape of the plurality of through holes 7C is not limited to a circular shape.

When viewed from the central axis direction, the area of the region in the exhaust gas pipeline 5 where the first shielding portion 7 is not arranged (that is, the opening 7G of the first shielding portion 7) is the total area of the plurality of through holes 7C. Greater than.

(2nd shield)
As shown in FIG. 3, the second shielding portion 8 has an annular portion 8A and a side wall portion 8B.
The annular portion 8A is a portion in which an opening 8C is formed in the radial center of the exhaust gas pipeline 5 and shields the flow in the first direction D1 on the radial outer side of the opening 8C. The outer diameter of the annular portion 8A coincides with the inner diameter of the exhaust gas pipeline 5. Further, the contact portion 8H of the annular portion 8A with the inner peripheral surface of the exhaust gas pipeline 5 extends downstream along the first direction D1.

The side wall portion 8B is a portion extending from the annular portion 8A to the central portion 7A of the first shielding portion 7 in the first direction D1. The side wall portion 8B partially surrounds the opening 8C of the annular portion 8A in the circumferential direction. That is, the side wall portion 8B projects in the first direction D1 from a part of the peripheral edge of the opening 8C.

As shown in FIG. 2A, the side wall portion 8B is arranged at a position overlapping the opening portion of the first shielding portion 7. In other words, the open portion 8D of the opening 8C of the annular portion 8A is arranged at a position facing the opening 7G of the first shielding portion 7 with respect to the central axis of the exhaust gas pipeline 5.

When viewed from the central axis direction, the central position of the open portion 8D in the circumferential direction faces the reducing agent injection position of the reducing agent supply unit 4 on the side wall portion 8B (that is, the central axis of the exhaust gas pipeline 5 is sandwiched between them). On the other side).

The first end portion 8E in the circumferential direction of the side wall portion 8B overlaps with the first end portion 7D in the circumferential direction of the peripheral edge portion 7B in the first shielding portion 7 when viewed from the central axis direction. Further, the second end portion 8F in the circumferential direction of the side wall portion 8B overlaps with the second end portion 7E in the circumferential direction of the peripheral edge portion 7B in the first shielding portion 7 when viewed from the central axis direction. That is, a part of the side wall portion 8B exists at a position overlapping the first shielding portion 7 when viewed from the central axis direction.

In this way, the first end portion 8E and the second end portion 8F of the side wall portion 8B overlap with the first end portion 7D and the second end portion 7E of the peripheral edge portion 7B, respectively, so that the exhaust gas flowing from the upstream side flows. The gas reliably collides with the side wall portion 8B. As a result, the stirring performance can be ensured while reducing the pressure loss.

The side wall portion 8B has a connecting portion 8G. As shown in FIG. 3, the connecting portion 8G is a portion provided at the upstream end of the side wall portion 8B. The connecting portion 8G has a shape in which the strip is annular in a direction in which the thickness direction coincides with the radial direction. As shown in FIG. 2A, the connecting portion 8G has an upstream end surface connected to a downstream surface of the central portion 7A of the first shielding portion 7.

[1-2. function]
Next, the mechanism for generating the swirling flow in the purification device 1 will be described.
In the purification device 1, the exhaust gas discharged from the exhaust gas purification unit 2 enters the exhaust gas pipeline 5 as it is without changing the direction of the flow.

In the exhaust gas pipeline 5, as shown in FIG. 4, the flow of the exhaust gas is first partially shielded by the central portion 7A of the first shielding portion 7. That is, the flow path of the exhaust gas is narrowed down to the opening 7G which is not blocked by the central portion 7A and the peripheral portion 7B, and the plurality of through holes 7C.

The exhaust gas that has passed through the opening 7G along the first direction D1 collides with the annular portion 8A of the second shielding portion 8. As a result, two swirling flows (in FIG. 4, only one swirling flow is shown) are formed so as to bypass the side wall portion 8B and head toward the opening 8C. Further, the flow of exhaust gas passing through the plurality of through holes 7C collides with the two swirling flows.

As a result, the reducing agent that collides with the side wall portion 8B and is atomized is caught in the flow of the exhaust gas and diffused and dispersed. As a result, the reducing agent and the exhaust gas that have passed through the exhaust gas pipeline 5 come into uniform contact with the reduction catalyst 31.

[1-3. effect]
According to the embodiment described in detail above, the following effects can be obtained.
(1a) The flow of the exhaust gas in the first direction D1 is guided to the outside of the side wall portion 8B of the second shielding portion 8 by the first shielding portion 7. The flow guided to the side wall portion 8B flows toward the opening 8C of the annular portion 8A while being divided into two flows by the side wall portion 8B. As a result, the flow path of the exhaust gas is extended, and two swirling flows in opposite directions having a swirling axis parallel to the first direction D1 are generated. Therefore, the reducing agent sprayed toward the side wall portion 8B is efficiently diffused. As a result, the evaporation of the reducing agent is promoted and the dispersibility is improved. Further, a part of the exhaust gas flow passes through the plurality of through holes 7C of the first shielding portion 7 and joins the two swirling flows. As a result, the reducing agent and the exhaust gas are effectively agitated.

(1b) It is not necessary to provide an introduction hole in the plate that closes the flow path, and the flow path diameter can be adjusted to an arbitrary size by the first shielding portion 7. Therefore, it is possible to suppress an increase in pressure loss while increasing the purification efficiency of exhaust gas.

(1c) When viewed from the central axis direction, the area of the region (that is, the opening 7G of the first shielding portion 7) in the exhaust gas pipeline 5 where the first shielding portion 7 is not arranged is the plurality of through holes 7C. Since it is larger than the total area of, the above-mentioned two swirling flows can be generated more reliably. As a result, the purification efficiency of the exhaust gas can be improved.

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(2a) In the exhaust gas purification device 1 of the above embodiment, when viewed from the central axis direction, the area in the exhaust gas pipeline 5 where the first shielding portion 7 is not arranged (that is, the opening of the first shielding portion 7). The area of 7G) does not necessarily have to be larger than the total area of the plurality of through holes 7C.

(2b) In the exhaust gas purification device 1 of the above embodiment, the first end portion 8E and the second end portion 8F in the circumferential direction of the side wall portion 8B are necessarily the first in the circumferential direction of the peripheral edge portion 7B when viewed from the central axis direction. It does not have to overlap with the first end 7D and the second end 7E.

(2c) In the exhaust gas purification device 1 of the above embodiment, the plurality of through holes 7C may not be arranged at equal intervals in an arc shape. For example, the plurality of through holes 7C may be arranged in a grid pattern or randomly.

(2d) In the exhaust gas purification device 1 of the above-described embodiment, the swirling flow generating unit 6 is integrated by assembling separately formed parts as the first shielding unit 7 and the second shielding unit 8. It may be composed of one integrally molded member.

(2e) In the exhaust gas purification device 1 of the above embodiment, the inner diameter of the exhaust gas purification unit 2 and / or the reduction unit 3 and the inner diameter of the exhaust gas pipeline 5 do not have to be the same. For example, the inner diameter of the exhaust gas purification unit 2 may be smaller than the inner diameter of the exhaust gas pipeline 5. In this case, the exhaust gas pipeline 5 has a tapered portion whose diameter is reduced from the downstream to the upstream.

Further, a connecting pipe may be further arranged between the exhaust gas purification unit 2 and the exhaust gas pipeline 5. This connecting pipe may be curved. By using the curved connecting pipe, the degree of freedom in arranging the exhaust gas purification unit 2 is increased.

(2f) The functions of one component in the above embodiment may be dispersed as a plurality of components, or the functions of the plurality of components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. In addition, at least a part of the configuration of the above embodiment may be added or replaced with the configuration of the other embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

[3. Example]
Next, a comparison between Example 1 and Comparative Example 1 performed to confirm the effect of the present disclosure will be described.

(Example 1)
The pressure loss in the swirling flow generating section 6 when the gas was supplied to the exhaust gas purifying device 1 in FIG. 1 and the uniformity of ammonia as a reducing agent were obtained by analysis.

Here, the uniformity γ of ammonia is a value calculated by the following equations (1), (2) and (3). In the following formula, n is the number of measurement points, Wi is the mass distribution of ammonia at each measurement point, and Wm is the average value of Wi.
Φi = {(Wi-Wm) ² } ^1/2 / Wm ・ ・ ・ (1)
Φ ＝ ΣΦi / n ・ ・ ・ (2)
γ = 1-Φ / 2 ・ ・ ・ (3)

(Comparative Example 1)
In a conventional exhaust gas purification device in which an introduction hole is provided in a plate that closes a flow path disclosed in Patent Document 1, pressure loss in a swirling flow generating portion and ammonia uniformity are measured under the same conditions as in Example 1. Obtained by analysis.

(result)
The uniformity of ammonia in Example 1 was almost the same as that in Comparative Example 1. Further, in Example 1, the pressure loss was reduced by about 80% as compared with Comparative Example 1. That is, in the first embodiment, it is presumed that the gas flow can be made uniform while reducing the pressure loss in the swirling flow generating portion.

1 ... Exhaust gas purification device, 2 ... Exhaust gas purification unit, 2A ... Exhaust port, 3 ... Reduction unit,
3A ... Introduction port, 4 ... Reducing agent supply unit, 5 ... Exhaust gas pipeline, 6 ... Swirling flow generator,
7 ... 1st shielding part, 7A ... central part, 7B ... peripheral part, 7C ... through hole, 7D ... 1st end part,
7E ... 2nd end, 7F ... Abutment, 7G ... Opening, 8 ... Second shielding, 8A ... Annulus,
8B ... side wall, 8C ... opening, 8D ... open, 8E ... first end, 8F ... second end,
8G ... Connection part, 21 ... Purification member, 22 ... Casing, 31 ... Reduction catalyst,
32 ... Casing.

Claims (4)

Exhaust gas purification device for internal combustion engine
An exhaust gas purification unit configured to reform or collect environmental pollutants in the exhaust gas,
A reducing unit provided on the downstream side of the exhaust gas purification unit in the flow direction of the exhaust gas and configured to reduce the exhaust gas in the presence of a reducing agent.
A reducing agent supply unit configured to supply the reducing agent to the exhaust gas on the upstream side of the reducing unit in the flow direction of the exhaust gas.
An exhaust gas pipeline that connects the exhaust port of the exhaust gas purification unit and the introduction port of the reduction unit,
A swirling flow generator installed in the exhaust gas pipeline and
With
The swirling flow generator
A first shielding portion configured to shield a part of the flow in the central axis direction of the exhaust gas pipeline, and
A second shield located downstream of the first shield and
Have,
The second shielding portion is
An annular portion having an opening formed in the radial center of the exhaust gas pipeline and configured to shield the flow in the central axial direction on the radial outer side of the opening.
A side wall portion that extends from the annular portion to the first shielding portion and partially surrounds the opening of the annular portion in the circumferential direction.
Have,
The first shielding portion is
A central portion that overlaps the opening of the annular portion when viewed from the central axis direction and is separated from the inner surface of the exhaust gas pipeline.
A peripheral portion including a plate-shaped portion extending from the central portion to the inner peripheral surface of the exhaust gas pipeline and having a plate surface orthogonal to the central axial direction .
A plurality of through holes provided in the plate-shaped portion and
Have,
The peripheral edge portion is arranged so as to at least overlap the outer edge of the opening of the annular portion in the radial direction of the open portion not surrounded by the side wall portion when viewed from the central axis direction.
The reducing agent supply unit is an exhaust gas purifying device that injects the reducing agent toward the side wall portion. The exhaust gas purification device according to claim 1.
An exhaust gas purification device in which the area of a region in the exhaust gas pipeline where the first shielding portion is not arranged is larger than the total area of the plurality of through holes when viewed from the central axis direction. The exhaust gas purification device according to claim 1 or 2.
An exhaust gas purification device in which the length of the contact portion between the peripheral edge portion and the inner peripheral surface of the exhaust gas pipeline in the circumferential direction is ½ or less of the inner peripheral length of the exhaust gas pipeline. The exhaust gas purification device according to any one of claims 1 to 3.
The first end of the circumferential direction of the side wall portion, together with the overlap with the first end portion of the circumferential direction of the periphery when seen from the axial direction, the second end portion of the circumferential direction of the side wall portions , it overlaps the second end of the circumferential direction of the periphery when seen from the axial direction, the exhaust gas purifying device.