JP2018115586A - Exhaust gas purification device - Google Patents

Abstract

The present invention provides an exhaust gas purification device that is excellent in exhaust gas purification efficiency by improving the diffusion effect of a reducing agent. 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 conduit, and a swirl flow generation unit. The reduction unit is provided on the downstream side of the exhaust gas purification unit, and reduces the exhaust gas in the presence of a reducing agent. The reducing agent supply unit supplies the reducing agent upstream of the reducing unit. The exhaust gas conduit communicates the exhaust gas purification unit and the reduction unit. The swirl flow generating unit is installed in the exhaust gas pipe line, and includes a first shielding unit and a second shielding unit disposed on the downstream side of the first shielding unit. The first shielding part includes a main body that shields the flow in the central axis direction of the exhaust gas pipe line, and a first passage hole that is provided outside the central axis of the main body and allows the exhaust gas to pass therethrough. The second shielding portion includes a main body that shields the flow in the central axis direction and the radial direction, and a second passage hole that allows the exhaust gas to pass radially inward. [Selection] Figure 1

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 regulations regarding the exhaust gas component of the internal combustion engine. If it is a diesel engine, exhaust gas purification members, such as a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a selective catalyst reduction (SCR) catalyst, etc. are used in combination for an exhaust gas purification device.

  Of these exhaust gas purification members, the SCR catalyst (hereinafter also referred to as “reduction catalyst”) is generally installed downstream of other catalysts or filters. SCR is a method of reducing NOx in exhaust gas to harmless nitrogen by a reducing agent and a reduction catalyst.

  In SCR, in order to make the reduction catalyst function efficiently and improve the exhaust gas purification rate, the reducing agent is mixed and dispersed uniformly in the exhaust gas, and the exhaust gas containing the reducing agent is not biased. It is necessary to contact the reduction catalyst.

  As a method of dispersing the reducing agent in the exhaust gas, there is a method of disposing a diffusion plate in the exhaust gas flow path. However, disposing the diffusion plate in the flow path causes a disadvantage that the pressure loss increases and the flow of exhaust gas is uneven.

  Therefore, an exhaust gas purification device has been proposed in which a spiral flow path is provided in the exhaust gas flow path and the reducing agent is diffused by a swirling flow generated by the spiral flow path (see Patent Document 1).

JP, 2014-190177, A

  According to the exhaust gas purification device of Patent Document 1, the reducing agent can be diffused by the swirling flow. However, in this exhaust gas purification device, the direction of the swirling flow is a single direction, and therefore the diffusion of the reducing agent may be biased. Further, in this exhaust gas purification device, reduction of pressure loss has not been sufficiently studied. Therefore, there is room for improvement in the diffusion effect of the reducing agent in the exhaust gas.

  One aspect of the present disclosure is to provide an exhaust gas purification device that is excellent in exhaust gas purification efficiency by improving the diffusion effect of the reducing agent.

  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 pipe, and a swirl flow generation unit. The exhaust gas purification unit reforms or collects 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 reduces the exhaust gas in the presence of a reducing agent. The reducing agent supply unit supplies the reducing agent to the exhaust gas upstream of the reducing unit in the flow direction of the exhaust gas. The exhaust gas conduit communicates 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 pipe. In addition, the swirl flow generating unit includes a first shielding unit and a second shielding unit disposed on the downstream side of the first shielding unit. The first shielding portion is provided on the outer side of the main axis of the exhaust gas pipe of the main body and the main axis of the exhaust gas pipe, and passes the exhaust gas in the direction of the central axis. A first passage hole. The second shielding portion includes a main body that shields the flow in the central axis direction and the radial direction of the exhaust gas pipe, and at least the exhaust gas that has been provided in the main body and that has passed through the at least one first passage hole. One second passage hole.

  According to such a configuration, first, the exhaust gas pipe is provided by the first shielding part that partially shields the flow of the exhaust gas in the central axis direction of the exhaust gas pipe line (hereinafter also referred to as “first direction”). A swirling flow having a swirling axis parallel to the radial direction of the road (hereinafter also referred to as “first swirling flow”) is generated. Next, the flow of the exhaust gas in the first direction is shielded, and the second direction is guided by the second shielding part that guides the exhaust gas in the radial direction of the exhaust gas pipe line (hereinafter also referred to as “second direction”). A swirling flow having parallel swirling axes (hereinafter also referred to as “second swirling flow”) is generated. In addition, when passing through the first shielding part and when passing through the second shielding part, the flow rate of the exhaust gas is increased by narrowing the flow path of the exhaust gas. Furthermore, according to the said structure, the raise of a pressure loss is also suppressed.

  Therefore, according to the above configuration, the reducing agent supplied into the exhaust gas is effectively diffused by the combination of the swirl flows having different swirl directions and the increase in the flow velocity of the exhaust gas. As a result, the exhaust gas purification efficiency in the reduction unit is increased.

  In one aspect of the present disclosure, the at least one first passage hole has a region that does not overlap the at least one second passage hole and the circumferential direction of the exhaust gas pipe line when viewed from the central axis direction of the exhaust gas pipe line. May be. According to such a configuration, the flow path of the exhaust gas in the swirl flow generation unit becomes longer, and the swirl flow can be generated more reliably.

  In one aspect of the present disclosure, the first shielding portion may have a plurality of first passage holes. Moreover, the 2nd shielding part may have a some 2nd passage hole. According to such a configuration, a plurality of first swirl flows and a plurality of second swirl flows can be generated. As a result, the diffusion effect of the reducing agent is promoted.

  In one aspect of the present disclosure, a plurality of first passage holes and a plurality of second passage holes may be alternately arranged in the circumferential direction of the exhaust gas pipe line as viewed from the central axis direction of the exhaust gas pipe line. Further, the distance between the centers of gravity of the first passage hole and the second passage hole adjacent in the circumferential direction of the exhaust gas pipe line may be constant. According to such a configuration, since the plurality of first swirl flows and the plurality of second swirl flows can be uniformly distributed in the exhaust gas pipe, the reducing agent diffusion effect is further improved.

  In one aspect of the present disclosure, the reducing agent supply unit may spray the reducing agent on the exhaust gas upstream of the second shielding unit in the exhaust gas flow direction. According to such a configuration, since the reducing agent is supplied during the swirling flow, the diffusion effect of the reducing agent is promoted. In addition, the flow path of the exhaust gas supplied with the reducing agent is extended at least by the second shielding part. As a result, mixing of the reducing agent is promoted, and the conduit from the reducing agent supply point to the reduction catalyst can be reduced.

1A is a schematic partial 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 swirl flow generation unit in the exhaust gas purification apparatus of FIG. 1A, and FIG. 2B is a schematic cross-sectional view taken along the line IIB-IIB of FIG. 2A. 3A is a schematic perspective view of the first shielding part in the swirling flow generating part of FIG. 2A, and FIG. 3B is a schematic partial perspective view of the second shielding part in the swirling flow generating part of FIG. 2A. . 4A is a schematic diagram showing exhaust gas streamlines in the swirl flow generation unit in the exhaust gas purifying apparatus of FIG. 1A, and FIG. 4B is exhaust gas in the swirl flow generation unit viewed from an angle different from FIG. 4A. It is a schematic diagram which shows the streamline of gas.

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
An exhaust gas purification device (hereinafter also simply referred to as “purification device”) 1 shown in FIGS. 1A and 1B is provided in an exhaust gas flow path of an internal combustion engine, and reduces 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 pipe 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 used particularly suitably as an exhaust gas purification device of a diesel engine. Examples of diesel engines include those used for driving or power generation in transportation equipment such as automobiles, railways, ships, 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), particulate matter (PM), sulfur oxide (SOx), hydrocarbons (HC), and the like.

  As shown in FIG. 1B, the exhaust gas purification unit 2 includes a purification member 21 for purifying exhaust gas and a cylindrical casing 22 that houses the purification member 21. 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), and a NOx adsorbent. 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 exhaust gas. The NOx adsorbent is a substance that adsorbs and removes NOx.

  As the purification member 21, a cylindrical body having a honeycomb structure is generally used. When the exhaust gas passes through the inside of the honeycomb structure, the environmental pollutant in the exhaust gas is modified by the catalytic metal included in the purification member 21 or captured by the purification member 21.

  1A and 1B, the exhaust gas purification unit 2 is arranged so that the flow direction of the exhaust gas in the interior is the vertical direction, that is, the central axis of the cylindrical 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 part>
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 by ammonia and a reduction catalyst and reforms it into harmless nitrogen. Ammonia, which is a reducing agent, is generally generated by injecting urea water into exhaust gas and hydrolyzing urea in the urea water.

  The reduction unit 3 includes a reduction catalyst 31 and a cylindrical casing 32 that houses the reduction catalyst 31. 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 via the exhaust gas pipe 5 in the exhaust gas flow direction. The reduction unit 3 is configured so that the flow direction of the exhaust gas in the interior 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 the central axis of the casing 22 of the exhaust gas purification unit 2 It is arranged in the direction that matches.

<Reducing agent supply unit>
The reducing agent supply unit 4 supplies the reducing agent to the exhaust gas upstream of the reducing unit 3 in the exhaust gas flow direction. In the present embodiment, as shown in FIGS. 1A and 1B, the reducing agent supply unit 4 is configured to spray the reducing agent inside the exhaust gas conduit 5. Specifically, the reducing agent supply unit 4 is upstream of the second shielding unit 8 and downstream of the first shielding unit 7 in the swirling flow generation unit 6 in the exhaust gas flow direction, that is, FIGS. 3A and 3B. Between the main body 7A of the first shielding part 7 and the first main body 8A of the second shielding part 8 shown in FIG. The injector sprays urea water as a reducing agent from the peripheral surface of the exhaust gas pipe 5 toward the central axis of the exhaust gas pipe 5.

  In addition, a well-known thing can be used for the injector of the reducing agent supply part 4. FIG. In FIGS. 1A and 1B, only the connecting pipe to the exhaust gas pipe 5 is shown as the reducing agent supply unit 4, and members such as an injector are not shown.

<Exhaust gas pipeline>
The exhaust gas conduit 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 pipe 5. A swirl flow generator 6 is disposed inside the exhaust gas pipe 5. A reducing agent supply unit 4 is connected to the peripheral surface of the exhaust gas pipe 5.

  The central axis direction of the exhaust gas pipe line 5 coincides with the central axis directions 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 conduit 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 pipe 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 swirl flow generator 6 is installed in the exhaust gas pipe 5 and generates a plurality of swirl flows in the exhaust gas. As shown in FIGS. 2A and 2B, the swirling flow generating unit 6 includes a first shielding unit 7 and a second shielding unit 8.

(First shielding part)
The first shielding part 7 partially shields the flow in the first direction D <b> 1, which is the central axis direction of the exhaust gas pipe 5, from the exhaust gas flowing in the exhaust gas pipe 5.

  As shown in FIG. 3A, the first shielding part 7 includes a main body 7A and a plurality of first passage holes 7B provided in the main body 7A. The first shielding part 7 shields the flow of the exhaust gas in the first direction D1 by the main body 7A, and allows the exhaust gas to pass in the first direction D1 only by the plurality of first passage holes 7B.

  The main body 7A is a plate-like member arranged in a direction in which the thickness direction coincides with the first direction D1. The outer shape of the main body 7A is a shape (that is, a disk shape) along the inner peripheral surface of the exhaust gas conduit 5. That is, the main body 7A closes the exhaust gas conduit 5 at a portion other than the plurality of first passage holes 7B to shield the flow of exhaust gas.

  3A, the main body 7A has a columnar protrusion 7C protruding toward the upstream side at a central portion including the central axis of the exhaust gas conduit 5. In other words, the main body 7A has a cylindrical recess formed on the downstream surface of the central portion. Since this recessed part is for assembling the 2nd shielding part 8 to the 1st shielding part 7, it can be abbreviate | omitted. That is, the main body 7A may have a flat plate shape without unevenness.

  In this embodiment, the 1st shielding part 7 has two 1st passage holes 7B. The two first passage holes 7B are provided outside the central axis of the exhaust gas conduit 5 of the main body 7A, and penetrate the main body 7A in the thickness direction (that is, the first direction D1). The two first passage holes 7B allow the exhaust gas reaching the main body 7A to pass in the first direction D1.

  The two first passage holes 7 </ b> B are slit-like through holes whose longitudinal direction is along the circumferential direction of the exhaust gas conduit 5. The two first passage holes 7B have the same length and width. Further, the two first passage holes 7B are arranged at positions facing each other across the central axis of the exhaust gas conduit 5 when viewed from the first direction D1. Accordingly, the two first passage holes 7 </ b> B are arranged at a certain distance in the circumferential direction of the exhaust gas pipe 5.

(Second shielding part)
The second shielding part 8 completely shields the flow in the first direction D1 from the exhaust gas that has passed through the two first passage holes 7B of the first shielding part 7, and also exhausts the exhaust gas from the exhaust gas pipe line 5. It guide | induces to the 2nd direction D2 which is a radial direction, and changes the direction of the flow of exhaust gas.

  As shown in FIG. 3B, the second shielding portion 8 includes a plate-like first main body 8A, a cylindrical second main body 8B, and a plurality of second passage holes 8C provided in the second main body 8B. . The second shielding portion 8 completely shields the flow of exhaust gas in the first direction D1 by the first main body 8A and the second main body 8B. Further, the second shielding portion 8 shields the flow of the exhaust gas in the second direction D2 by the second main body 8B, and allows the exhaust gas to pass inside the second direction D2 only by the plurality of second passage holes 8C.

  The first main body 8A is a plate-like member arranged in a direction in which the thickness direction coincides with the first direction D1. The outer shape of the first main body 8 </ b> A is a shape along the inner peripheral surface of the exhaust gas conduit 5, similar to the main body 7 </ b> A of the first shielding portion 7. The first main body 8 </ b> A has an opening at a central portion including the central axis of the exhaust gas conduit 5. A second main body 8B is connected to the upstream surface of the first main body 8A so as to close the opening.

  The second main body 8B is a cylindrical body that is closed on the upstream side and opened on the downstream side. 3B, the second main body 8B seems to be open on the upstream side as well, but the upstream side of the second main body 8B is the first side in the coupled state with the first shielding part 7. The shield 7 is blocked by the downstream surface of the main body 7A. The downstream end of the second main body 8B is connected to the opening of the first main body 8A.

  In the present embodiment, the second shielding part 8 has two second passage holes 8C. The two second passage holes 8C are provided on the peripheral surface of the second main body 8B and penetrate the second main body 8B in the radial direction (that is, the second direction D2). The two second passage holes 8C allow the exhaust gas colliding with the first main body 8A to pass through in the second direction D2, that is, inside the second main body 8B.

  The two second passage holes 8 </ b> C are slit-like through holes whose longitudinal direction is along the circumferential direction of the exhaust gas conduit 5. The length and width of the two second passage holes 8C are the same. Further, the two second passage holes 8C are arranged at positions facing each other across the central axis of the exhaust gas pipe line 5 when viewed from the first direction D1. Therefore, the two second passage holes 8 </ b> C are arranged at a certain distance in the circumferential direction of the exhaust gas pipe 5.

(Positional relationship between the first passage hole and the second passage hole)
In the present embodiment, the two first passage holes 7 </ b> B have regions that do not overlap with the two second passage holes 8 </ b> C and the exhaust gas pipe 5 in the circumferential direction when viewed from the first direction D <b> 1. That is, the two first passage holes 7B are arranged so as not to overlap at least partly with the two second passage holes 8C in the circumferential direction.

  2A and 2B, when viewed from the first direction D1, in each of the two first passage holes 7B, both end portions in the circumferential direction of the exhaust gas pipe 5 are two second passages. It arrange | positions so that it may each overlap with the hole 8C. However, the two first passage holes 7B and the two second passage holes 8C do not have to overlap at all in the circumferential direction of the exhaust gas conduit 5, and are disposed so that only one end portion thereof overlaps. Also good.

  In the present embodiment, the centroids of the two first passage holes 7B and the centroids of the two second passage holes 8C are arranged at equal intervals in the circumferential direction of the exhaust gas conduit 5. That is, all the distances between the centers of gravity of the first passage hole 7B and the second passage hole 8C adjacent in the circumferential direction of the exhaust gas pipe line 5 are constant.

[1-2. function]
Next, the generation mechanism of 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 pipe 5 as it is without changing the flow direction.

  In the exhaust gas conduit 5, the flow of the exhaust gas is first partially shielded by the main body 7 </ b> A of the first shielding part 7. That is, the flow path of the exhaust gas is restricted to the two first passage holes 7B. Therefore, a first swirling flow having a swirling axis perpendicular to the first direction D1 is generated in the first shielding portion 7 as indicated by an arrow in FIG. 4A. In the present embodiment, a plurality of first swirl flows are formed by the two first passage holes 7B.

  Next, the exhaust gas that has passed through the two first passage holes 7 </ b> B collides with the plate surface of the first main body 8 </ b> A of the second shielding portion 8. Thereafter, the exhaust gas changes its flow in the second direction D2, passes through the two second passage holes 8C, and enters the second body 8B. At this time, the flow path of the exhaust gas is narrowed again by the two second passage holes 8C.

  In the second shielding part 8, as indicated by an arrow in FIG. 4B, a second swirling flow having a swirling axis perpendicular to the second direction D2 is generated. In the present embodiment, a plurality of second swirl flows are formed by the two second passage holes 8C.

  The exhaust gas that has entered the second main body 8B of the second shielding portion 8 flows again in the first direction D1, and is discharged from the opening on the downstream side of the second main body 8B. The exhaust gas discharged from the opening of the second main body 8B is introduced into the reduction unit 3. Since the diameter of the opening of the second main body 8B is smaller than the diameter of the inlet 3A of the reducing unit 3, the flow rate of the exhaust gas decreases when being introduced into the reducing unit 3. As a result, the exhaust gas diffuses in the reduction unit 3 and comes into homogeneous contact with the reduction catalyst 31.

[1-3. effect]
According to the embodiment detailed above, the following effects can be obtained.
(1a) A plurality of first swirling flows are generated by the first shielding part 7 that partially shields the flow of the exhaust gas in the first direction D1. Next, a plurality of second swirling flows are generated by the second shielding portion 8 that completely shields the flow of the exhaust gas in the first direction D1 and guides the exhaust gas in the second direction D2. By these swirl flows, the reducing agent supplied into the exhaust gas is effectively diffused.

  (1b) When passing through the first shielding part 7 and when passing through the second shielding part 8, the flow rate of the exhaust gas is increased by narrowing the flow path of the exhaust gas. Therefore, the speed of the above-mentioned swirl flow is increased, and the diffusion of the reducing agent is promoted.

  (1c) On the downstream side of the second shielding part 8, the exhaust gas flow path becomes wider. Therefore, the flow rate of the exhaust gas is reduced, and the flow of the exhaust gas supplied to the reducing unit 3 becomes uniform, so that the exhaust gas is efficiently reduced.

  (1d) The swirl flow generator 6 generates the swirl flow described above while causing the exhaust gas to flow toward the central axis. Therefore, it is suppressed that the reducing agent contained in exhaust gas adheres to the side surface of the exhaust gas pipe line 5 having a relatively low temperature. As a result, the deposit of the reducing agent can be reduced.

  (1e) Since the plurality of first passage holes 7B are arranged so as not to overlap at least partially in the circumferential direction of the plurality of second passage holes 8C and the exhaust gas pipe line 5 when viewed from the first direction D1, The exhaust gas flow path in the swirling flow generating section 6 is extended. Thereby, a plurality of swirl flows can be generated more reliably.

  (1f) Since the plurality of first passage holes 7B and the plurality of second passage holes 8C are alternately arranged in the circumferential direction of the exhaust gas pipe line 5 when viewed from the first direction D1, a plurality of first swirl And a plurality of second swirl flows are generated. Thereby, the diffusion effect of the reducing agent is promoted.

  (1g) Since the reducing agent supply unit 4 sprays the reducing agent between the first shielding unit 7 and the second shielding unit 8 in the exhaust gas flow direction, the reducing agent is supplied during the swirling flow. As a result, the diffusion effect of the reducing agent is further promoted. Further, the flow path of the exhaust gas supplied with the reducing agent is extended by the second shielding unit 8. As a result, mixing of the reducing agent is promoted, and the conduit from the reducing agent supply point to the reduction catalyst can be reduced.

[2. Other Embodiments]
As mentioned above, although embodiment of this indication was described, it cannot be overemphasized that this indication can take various forms, without being limited to the above-mentioned embodiment.

  (2a) In the exhaust gas purification apparatus 1 of the above embodiment, the first shielding portion 7 and the second shielding portion 8 do not necessarily have a plurality of passage holes, and may have at least one passage hole.

(2b) In the exhaust gas purification apparatus 1 of the above embodiment, the positions and shapes of at least one first passage hole and at least one second passage hole are not limited to those described above.
In other words, when viewed from the first direction, at least one second passage hole does not have a region where it does not overlap in the circumferential direction of the exhaust gas conduit 5 with respect to at least one first passage hole. Good. Conversely, at least one first passage hole may completely overlap the circumferential direction of the exhaust gas pipe line 5 with respect to at least one second passage hole.

  Further, the plurality of first passage holes and the plurality of second passage holes may not be arranged at equal intervals. Furthermore, as viewed from the first direction, the plurality of first passage holes and the plurality of second passage holes may not be alternately arranged in the circumferential direction of the exhaust gas pipe 5.

  (2c) In the exhaust gas purifying apparatus 1 of the above embodiment, the swirl flow generating unit 6 is integrated by assembling components separately formed as the first shielding unit 7 and the second shielding unit 8. Alternatively, it may be composed of a single member formed integrally. On the contrary, the 1st shielding part 7 and the 2nd shielding part 8 may be comprised as an independent member, respectively, and you may arrange | position both apart in the flow direction of exhaust gas.

  (2d) In the exhaust gas purification apparatus 1 of the above embodiment, the reducing agent supply unit 4 does not necessarily have to inject the reducing agent between the first shielding unit 7 and the second shielding unit 8 in the exhaust gas flow direction. Absent. For example, a reducing agent may be supplied to the upstream side of the first shielding part 7, or a reducing agent may be supplied to the downstream side of the second shielding part 8. However, from the viewpoint of the diffusion effect of the reducing agent, it is preferable to supply the reducing agent at least upstream of the second shielding part 8.

  (2e) The functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the 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 swirl flow generation unit 6 when gas was supplied to the exhaust gas purification device 1 of FIG. 1 was obtained by analysis.

(Comparative Example 1)
In the exhaust gas purification device 1 of FIG. 1, the swirl flow generating unit 6 is replaced with a swirl flow generating unit having a shape in which a plurality of through holes are provided in a disk, and pressure loss in the swirl flow generating unit is analyzed under the same conditions as in the first embodiment. Determined by

(result)
In Example 1, the pressure loss was reduced by about 20% compared to Comparative Example 1. That is, in Example 1, it is estimated that the pressure loss in the swirl flow generation unit is low and the gas flow can be made uniform.

DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification apparatus, 2 ... Exhaust gas purification part, 2A ... Discharge port, 3 ... Reduction part,
3A ... inlet, 4 ... reducing agent supply unit, 5 ... exhaust gas conduit, 6 ... swirl flow generating unit,
7 ... 1st shielding part, 7A ... Main body, 7B ... 1st passage hole, 7C ... Projection,
8 ... 2nd shielding part, 8A ... 1st main body, 8B ... 2nd main body, 8C ... 2nd passage hole,
21 ... Purifying member, 22 ... Casing, 31 ... Reduction catalyst, 32 ... Casing.

Claims (5)

An exhaust gas purification device for an internal combustion engine,
An exhaust gas purification unit for reforming or collecting environmental pollutants in the exhaust gas;
A reducing unit that is provided downstream of the exhaust gas purification unit in the flow direction of the exhaust gas, and that reduces the exhaust gas in the presence of a reducing agent;
A reducing agent supply unit that supplies a reducing agent to the exhaust gas upstream of the reducing unit in the flow direction of the exhaust gas;
An exhaust gas conduit communicating the exhaust port of the exhaust gas purification unit and the introduction port of the reduction unit;
A swirl flow generator installed in the exhaust gas pipe;
With
The swirl flow generation unit includes a first shielding unit and a second shielding unit disposed on the downstream side of the first shielding unit,
The first shielding portion is provided on the outer side of the main axis of the exhaust gas conduit of the main body and the main body that shields the flow in the central axis direction of the exhaust gas conduit, and discharges the exhaust gas in the central axial direction. And at least one first passage hole that passes through
The second shielding portion includes a main body that shields the flow in the central axis direction and the radial direction of the exhaust gas pipe, and the exhaust gas that is provided in the main body and passes through the at least one first passage hole. An exhaust gas purifier having at least one second passage hole that passes radially inward. The exhaust gas purification device according to claim 1,
The at least one first passage hole has an area that does not overlap with the at least one second passage hole in the circumferential direction of the exhaust gas pipe line when viewed from the central axis direction of the exhaust gas pipe line. apparatus. The exhaust gas purifying device according to claim 1 or 2,
The first shielding part has a plurality of the first passage holes,
The second shielding unit is an exhaust gas purification device having a plurality of the second passage holes. An exhaust gas purification device according to claim 3,
The plurality of first passage holes and the plurality of second passage holes are alternately arranged in the circumferential direction of the exhaust gas passage as viewed from the central axis direction of the exhaust gas passage.
The exhaust gas purifying apparatus, wherein a distance between the centers of gravity of the first passage hole and the second passage hole adjacent in the circumferential direction of the exhaust gas pipe is constant. It is an exhaust-gas purification apparatus of any one of Claims 1-4, Comprising:
The exhaust gas purification device, wherein the reducing agent supply unit sprays the reducing agent on the exhaust gas upstream of the second shielding unit in the flow direction of the exhaust gas.