JP2014234815A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

An exhaust purification device for an internal combustion engine capable of uniformly mixing a reducing agent and exhaust at a shorter distance than before. A reducing agent supply device 2 provided in an exhaust pipe 11 of an engine, a downstream catalytic converter 4 provided in an exhaust pipe 11 downstream of the reducing agent supply device 2, and an exhaust pipe 11 therebetween. The mixer 3 includes a first member 31 having a bottomless, hollow, substantially conical shape whose diameter increases toward the downstream side, and a first member 31 inside the first member 31. A second member 32 having a substantially conical shape with a diameter smaller than that of the first member 31, which is provided with a gap between the inner wall surface of the first member 31 and is hollow and expands toward the downstream side. The first member 31 and the second member 32 are provided on the same axis X, and through holes 310 and 320 are formed at the respective apexes, and the reducing agent supply apparatus 2 has the through hole 310 from the axis X. 320, the reducing agent being supplied through 320, An exhaust purification device 10 down. [Selection] Figure 2

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine. More specifically, the present invention relates to an exhaust gas purification apparatus for an internal combustion engine including a mixer that mixes a reducing agent supplied into an exhaust passage of the internal combustion engine and exhaust gas.

Conventionally, a technique for purifying NOx by providing a selective reduction catalyst in an exhaust pipe of an internal combustion engine (hereinafter also referred to as “engine”) and supplying a reducing agent from an exhaust pipe upstream of the selective reduction catalyst is known. ing. In this technique, usually, a mixer for mixing the exhaust flowing in the exhaust pipe and the supplied reducing agent is provided in the exhaust pipe. Specifically, for example, a technique has been proposed in which a mixer is provided on the upstream side of an exhaust pipe and a swirling flow is generated by this mixer to mix a reducing agent such as NH ₃ gas and exhaust (for example, a patent) Reference 1 and 2).

By the way, the engine is provided in the engine room in front of the vehicle, and the exhaust pipe extends from the exhaust port of the engine and reaches the rear end portion of the vehicle along the under floor of the vehicle. Therefore, the exhaust pipe is divided into an engine section in the engine room and an underfloor section outside the engine room because of its structure. The engine section is maintained at a relatively high temperature because the heat from the exhaust flowing through the exhaust pipe from the engine to this section is small and the distance to the high-temperature engine is short and is warmed by the heat of the engine.
However, in addition to the engine, various devices such as an intake system and a fuel injection system are arranged in the engine room. In addition, a filter that collects particulate matter is preferentially placed in the engine section so that energy efficiency is advantageous because it is necessary to appropriately perform a regeneration process that burns and removes the collected particulate matter. . Therefore, the selective reduction catalyst is often arranged in the underfloor section having a high degree of freedom in arrangement.

However, the inside of the underfloor section is maintained at a lower temperature than the engine section because the heat from the exhaust flowing through the exhaust pipe from the engine section to this section is large and the distance to the engine is long and it is not warmed by the engine heat. The For this reason, the temperature of the selective reduction catalyst may not reach a temperature suitable for reducing NOx.
Therefore, it is conceivable to place the filter in the engine section after supporting the selective reduction catalyst on the filter. As a result, the inside of the narrow engine section can be used effectively, and the temperature of the exhaust gas flowing into the selective reduction catalyst quickly reaches the activation temperature range of the selective reduction catalyst, so that the NOx purification rate can be improved. Further, various exhaust system devices disposed under the floor of the vehicle are abolished, and the cost can be reduced.

JP 2009-121396 A JP 2010-71240 A

  However, when the selective reduction catalyst is arranged in a narrow engine section, it is not possible to ensure a sufficient distance between the selective reduction catalyst and the mixer provided upstream thereof. Therefore, although there are many conventional techniques for forming a flow of exhaust with an upstream mixer and uniformly mixing the reducing agent and exhaust, in order to uniformly mix the reducing agent and exhaust at a shorter distance, There is room for further improvement.

  The present invention has been made in view of the above, and an object of the present invention is to provide an exhaust purification device for an internal combustion engine that can uniformly mix a reducing agent and exhaust at a shorter distance than before.

  In order to achieve the above object, the present invention provides a reducing agent supply means (provided in an exhaust passage (for example, an exhaust pipe 11 to be described later) of an internal combustion engine (for example, an engine to be described later), For example, an injector 20), which will be described later, and an exhaust purification means (for example, downstream, which will be described later) are provided in an exhaust passage downstream of the reducing agent supply means and purify the exhaust gas by the reducing agent supplied by the reducing agent supply means. A mixer (for example, a mixer 3 to be described later) provided in an exhaust passage between the catalytic converter 4) and the reducing agent supply means and the exhaust purification means, and mixes the reducing agent supplied by the reducing agent supply means and the exhaust gas. ), And the mixer has a bottomless, hollow, substantially conical shape that increases in diameter toward the downstream side. A first member (for example, a first member 31 described later) and a gap between the first member and the inner wall surface of the first member are provided inside the first member, and the diameter is increased toward the downstream side. A second member having a substantially conical shape that is hollow at the bottom and has a smaller diameter than the first member (for example, a second member 32 to be described later), and the first member and the second member are identical to each other. While being provided on an axis (for example, an axis X described later), a through hole (for example, a later described through hole 310, 320) is formed at each apex portion, and the reducing agent supply means passes through the axis from the axis. An exhaust emission control device for an internal combustion engine is provided, wherein a reducing agent is supplied through a hole.

In the present invention, a mixer is constituted by a first member and a second member that have a bottomless, hollow, substantially conical shape that increases in diameter toward the downstream side and have different diameters. Specifically, the second member having a diameter smaller than that of the first member is arranged with a gap between the first member and the inner wall surface of the first member, and both the two members are on the same axis. Arrange the members. Furthermore, a through-hole is formed in each vertex part of both members, and a reducing agent is supplied through these through-holes from an axial line.
As a result, the reducing agent supplied through the through-holes formed at each apex portion is diffused into the exhaust gas by the exhaust gas flowing downstream through the substantially conical first member and the second member. Promoted. Therefore, according to the present invention, the reducing agent and the exhaust gas can be uniformly mixed at a shorter distance than before.

  It is preferable that at least one through hole (for example, a through hole 321 described later) is formed in the side surface of the second member.

In the present invention, at least one through hole is formed in the side surface of the second member disposed on the inner side. As a result, the reducing agent supplied through each apex portion is promoted to diffuse into the exhaust gas by the exhaust gas flowing in from the through hole formed in the side surface portion of the second member. Therefore, according to the present invention, the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than before.
Moreover, a pressure loss can also be reduced more by forming a through-hole in the side part of a 2nd member.

  It is preferable that at least one through-hole (for example, through-holes 311 and 312 described later) is formed in the side surface of the first member.

In the present invention, at least one through hole is formed in the side surface of the first member disposed on the outside. As a result, the reducing agent supplied through each apex portion flows into the exhaust gas by the exhaust gas flowing from the through hole formed in the side surface portion of the first member and flowing downstream through the second member. Spreading is promoted. Therefore, according to the present invention, the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than before.
Moreover, a pressure loss can also be reduced more by forming a through-hole in the side part of a 1st member.

  The through hole formed in the side surface portion of the second member and the through hole formed in the side surface portion of the first member are arranged so as to be shifted from each other in the circumferential direction when viewed from the downstream side in the axial direction. It is preferable.

In this invention, the through-hole formed in the side surface portion of the second member and the through-hole formed in the side surface portion of the first member are arranged so as to be shifted from each other in the circumferential direction when viewed from the downstream side in the axial direction. Thus, both members are arranged.
Here, when the through hole formed in the side surface portion of the second member and the through hole formed in the side surface portion of the first member are on a straight line along the axial direction, the exhaust gas flows on the straight line. As a result, the inflow of exhaust gas between the two members cannot be promoted, and the effect of promoting the diffusion of the reducing agent by providing the through holes in the side surface portions of the two members cannot be sufficiently obtained. On the other hand, according to the present invention, since the through holes formed in the side surfaces of both members are displaced from each other in the circumferential direction when viewed from the downstream side in the axial direction, the exhaust between the two members is performed. Can be promoted. Therefore, diffusion of the reducing agent into the exhaust can be promoted, and the reducing agent and the exhaust can be uniformly mixed at a shorter distance than before.

  The through hole formed in the side surface portion of the first member has a through hole formed at a position not overlapping the second member when viewed from the downstream side in the axial direction (for example, a through hole 312 described later). Is preferably included.

  In this invention, the through-hole of the side part of the 1st member arrange | positioned outside is formed also in the position which does not overlap with a 2nd member when it sees from the downstream of an axial direction. Thus, the exhaust gas flowing between the two members can be directed to the radial center of the exhaust passage by the exhaust gas flowing from the through hole in the side surface portion of the first member formed at a position not overlapping the second member. . Therefore, according to the present invention, the reducing agent uniformly mixed in the exhaust gas can be efficiently supplied to the exhaust gas purification means on the downstream side.

  The reducing agent supply means is configured to supply a reducing agent to a plurality of locations, and supplies the reducing agent to at least the inside of the second member and the gap between the first member and the second member. preferable.

  In this invention, a reducing agent is supplied to at least the inside of the second member and the gap between the first member and the second member. Thereby, since the reducing agent can be supplied to the gap between at least the inner side of the second member and both members from the axial line through the through holes at the apexes, the diffusion of the reducing agent into the exhaust can be promoted. Reducing agent and exhaust can be mixed more uniformly at a short distance.

  The reducing agent supply means is configured to supply a reducing agent to a plurality of locations, and supplies the reducing agent to at least the inside of the second member and the outside of the first member, and the outer peripheral tip of the first member. A gap is formed between the inner wall surface of the exhaust passage or the inner wall surface of a case member (for example, a cylindrical portion 333 of the case member 33 described later) that accommodates the first member and the second member. Preferably it is.

  In the present invention, the reducing agent is supplied at least to the inside of the second member and the outside of the first member. Moreover, a clearance gap is formed in the outer peripheral front-end | tip part of a 1st member between the inner wall surface of an exhaust passage or the inner wall surface of the case member which accommodates a 1st member and a 2nd member. Thereby, since the reducing agent can be supplied to at least the inner side of the second member and the outer side of the first member through the through-holes of the respective apex portions from the axial line, it is possible to promote the diffusion of the reducing agent into the exhaust gas. Even at a short distance, the reducing agent and exhaust can be mixed more uniformly.

  It is preferable that the diameter of the through hole formed at the apex portion of the second member is smaller than the diameter of the through hole formed at the apex portion of the first member.

  In this invention, the diameter of the through hole formed at the apex portion of the second member is set smaller than the diameter of the through hole formed at the apex portion of the first member. Thereby, a part of reducing agent supplied from the axis can be efficiently supplied to the gap between the two members. Therefore, according to the present invention, the diffusion of the reducing agent into the exhaust gas can be further promoted, and the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than before.

  The reducing agent supply means extends along the axial direction from the upstream side of the first member to the downstream side of the second member, and includes each of the first member and the second member. A reducing agent supply pipe (for example, a second supply pipe 22 described later) inserted through each through hole formed at the apex is configured, and the reducing agent supply pipe includes a plurality of reducing agent injection ports in the axial direction. The reducing agent injection port includes a first injection port (for example, a first injection port 221 described later) for injecting a reducing agent to the outside of the first member, and the first member and the second member. A second injection port (for example, a second injection port 222 described later) that injects a reducing agent into the gap, and a third injection port (for example, a third injection port 223 described later) that injects the reducing agent inside the second member. ) And the like.

In this invention, a reducing agent supply pipe extending along the axial direction from the upstream side of the first member to the downstream side of the second member is provided, and the reducing agent supply pipe is provided at each vertex of both members. It is made to pass through each formed through-hole. The reducing agent supply pipe has a first injection port for injecting the reducing agent to the outside of the first member, a second injection port for injecting the reducing agent into the gap between the two members, and a reducing agent on the inside of the second member. And a third injection port for injecting.
As a result, the reducing agent can be supplied to the inside of the second member, the gap between the two members, and the outside of the first member, and the supplied reducing agent is exhausted by the exhaust gas flowing downstream through both of the substantially conical members. Can diffuse efficiently inside. Therefore, according to the present invention, the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than before.

The reducing agent is preferably NH ₃ gas or liquid reducing agent mixed with gas.

In the present invention, NH ₃ gas or liquid reducing agent mixed with gas is used as the reducing agent. Thereby, the above-mentioned effect is reliably show | played by supplying a gaseous reducing agent to a mixer.

  According to the present invention, there is provided an exhaust emission control device for an internal combustion engine capable of uniformly mixing a reducing agent and exhaust at a shorter distance than before.

1 is a diagram illustrating a configuration of an exhaust gas purification apparatus for an internal combustion engine according to a first embodiment of the present invention. It is a perspective view of the mixer and injector which concern on the said embodiment. It is the figure which looked at the mixer and injector which concern on the said embodiment from the downstream of the axial direction. It is the figure which looked at the mixer and injector which concern on the said embodiment from the upstream of the axial direction. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is sectional drawing which shows the structure of the injector which concerns on the said embodiment, (a) is BB sectional drawing of FIG. 5, (b) is CC sectional view taken on the line of FIG. 5, (c) FIG. 6 is a cross-sectional view taken along the line DD of FIG. It is a figure which shows the flow of the exhaust_gas | exhaustion and reducing agent in the mixer which concerns on the said embodiment. It is a figure which shows the structure of the mixer and injector which concern on 2nd Embodiment of this invention, its exhaust_gas | exhaustion, and the flow of a reducing agent. It is a perspective view of a mixer and an injector concerning comparative example 1. It is a perspective view of a mixer and an injector concerning comparative example 2. 6 is a diagram illustrating UI values of Example 1, Comparative Example 1, and Comparative Example 2. FIG. It is a figure which shows the relationship between the exhaust flow volume of Example 1 and Comparative Example 2, and a back pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, in the description of the second embodiment, the same reference numerals are given to configurations common to the first embodiment, and the description thereof is omitted.

[First Embodiment]
FIG. 1 is a diagram showing a configuration of an exhaust emission control device for an internal combustion engine according to a first embodiment of the present invention. The exhaust emission control device 10 according to the present embodiment is provided in an engine room in front of the vehicle, that is, in an engine section of the exhaust pipe 11. The exhaust purification device 10 is preferably used as an exhaust purification device for a lean burn operation type gasoline engine or diesel engine.

  As shown in FIG. 1, the exhaust purification device 10 includes an upstream catalytic converter 1, a reducing agent supply device 2, a mixer 3, and a downstream catalytic converter 4 in order from the upstream side. The exhaust pipe 11 on the upstream side of the exhaust purification apparatus 10 is connected to an exhaust manifold extending from the exhaust port of the engine.

The upstream catalytic converter 1 is configured by supporting an oxidation catalyst on a flow-through honeycomb support. HC and CO contained in the exhaust discharged from the engine are oxidized by the oxidation catalyst while passing through the upstream catalytic converter 1. Further, NO contained in the exhaust is also oxidized to NO ₂ in the process of passing through the upstream catalytic converter 1. Most of the NOx contained in the exhaust in the engine section is NO, and almost no NO ₂ is contained. Therefore, by oxidizing NO in the upstream catalytic converter 1 to generate NO ₂ , the NO ₂ / NOx ratio of the exhaust gas flowing into the downstream catalytic converter 4 to be described later is reduced, and the NOx purification performance in the SCR catalyst is optimized. Can be raised to 0.5.

The reducing agent supply device 2 includes an injector 20 that supplies NH ₃ gas as a reducing agent from the upstream side of the mixer 3 described later. The injector 20 will be described in detail later.
Note that the reducing agent supply device 2 may be configured to supply a liquid reducing agent such as urea water mixed with gas instead of NH ₃ gas.

The mixer 3 mixes the reducing agent such as NH ₃ gas supplied by the reducing agent supply device 2 and the exhaust gas with the exhaust gas so that the reducing agent uniformly mixed in the exhaust gas with respect to the downstream catalytic converter 4 described later is mixed. Supply. The mixer 3 will be described in detail later.

The downstream catalytic converter 4 includes a selective reduction catalyst (hereinafter, referred to as “reduction catalyst”) in each cell of the wall flow type honeycomb support in which a plurality of cells partitioned by porous walls are alternately sealed on the upstream side and the downstream side. It comprises a filter with selective reduction catalyst (hereinafter referred to as “SCRF”) on which “SCR catalyst” is carried.
Particulate matter (hereinafter referred to as “PM”) contained in the exhaust discharged from the engine is collected in the process of passing through the pores of the porous wall of the SCRF. When PM accumulates on the SCRF, the back pressure increases and the fuel consumption may deteriorate. Accordingly, when the PM deposition amount of the SCRF exceeds a predetermined amount, the filter regeneration process for burning and removing the PM collected by the SCRF is appropriately executed by raising the temperature of the SCRF to about 600 ° C.

The SCR catalyst supported on the SCRF selectively reduces NOx in the exhaust under an atmosphere in which NH ₃ exists. Specifically, when NH ₃ gas is supplied from the reducing agent supply device 2 described above, the reactions of the following reaction formulas (1) to (3) proceed to selectively reduce NOx in the exhaust gas. .
[Chemical 1]
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O... Reaction formula (1)
4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O ... Reaction formula (2)
6NO ₂ + 8NH ₃ → 7N ₂ + 12H ₂ O ... Reaction formula (3)

Further, SCR catalyst has a function of reducing NOx in the exhaust in NH _3, has a function of storing NH ₃ by a predetermined amount (storage). When the NH ₃ storage amount of the SCR catalyst exceeds the maximum NH ₃ storage amount, which is the maximum amount that can be stored, NH ₃ slips downstream. The NH ₃ stored in the SCR catalyst in this manner is appropriately consumed for the reduction of NOx in the exhaust gas together with the NH ₃ supplied from the reducing agent supply device 2.

Hereinafter, the mixer 3 and the injector 20 according to the present embodiment will be described in detail.
FIG. 2 is a perspective view of the mixer 3 and the injector 20 according to the present embodiment. As described above, the mixer 3 and the injector 20 are provided between the upstream catalytic converter 1 and the downstream catalytic converter 4. The reducing agent NH ₃ gas supplied from the injector 20 is uniformly mixed with the exhaust gas by the mixer 3.

As shown in FIG. 2, the mixer 3 includes a first member 31, a second member 32, and a case member 33.
The first member 31 is an umbrella-shaped member that has a bottomless, hollow, substantially conical shape that increases in diameter toward the downstream side. The first member 31 is disposed outside a second member 32 to be described later, and the outer peripheral tip of the first member is disposed downstream of the outer peripheral tip of the second member 32.
A through hole through which an injector 20 described later is inserted is formed at the apex of the first member 31.

Similar to the first member 31, the second member 32 is an umbrella-shaped member having a diameter that increases toward the downstream side and has a hollow, substantially conical shape. The second member 32 is substantially similar to the first member 31, and its diameter is smaller than that of the first member 31. The second member 32 is disposed on the same axis X as the first member 31 and is disposed inside the first member 31 with a gap between the inner wall surface of the first member 31.
Similar to the first member 31, a through hole into which an injector 20 described later is inserted is formed at the apex portion of the second member 32. In addition, the diameter of the through-hole formed in the vertex part of the 2nd member 32 and the through-hole formed in the vertex part of the 1st member 31 is the same.

The case member 33 is for fixing the mixer 3 in the exhaust pipe 11. The case member 33 connects the first annular part 331 provided on the upstream side, the second annular part 332 having a larger diameter than the first annular part 331 provided on the downstream side, and the annular part. A cylindrical portion 333 that increases in diameter as it goes from the first annular portion 331 toward the second annular portion 332.
However, the case member 33 is not an essential configuration, and the first member 31 and the second member may be provided directly in the exhaust pipe 11 without using the case member.

The injector 20 includes a first supply pipe 21 provided perpendicular to the axis X in the first annular portion 331 and a first supply pipe 21 extending from the first supply pipe 21 to the downstream side in the axis X direction. 2 supply pipes 22. The second supply pipe 22 of the injector 20 is inserted through a through hole formed at each vertex of the first member 31 and the second member 32 described above.
In the present embodiment, the second supply pipe 22 of the injector 20 is fitted in the through holes formed in the respective apex portions of the first member 31 and the second member 32 described above, but is not limited thereto. , May be inserted with a gap.

FIG. 3 is a view of the mixer 3 and the injector 20 according to the present embodiment as seen from the downstream side in the axis X direction. FIG. 4 is a view of the mixer 3 and the injector 20 according to the present embodiment as viewed from the upstream side in the axis X direction.
As shown in FIG. 3 and FIG. 4, four through holes 311 arranged at intervals of 90 degrees in the circumferential direction at positions overlapping the second member 32 in the side surface portion of the first member 31 arranged on the outside. Then, four through holes 312 are formed at positions that do not overlap the second member 32 at intervals of 90 degrees in the circumferential direction. The through holes 311 and the through holes 312 are formed so that their circumferential positions are the same.

  As shown in FIGS. 3 and 4, four through-holes 321 arranged at intervals of 90 degrees in the circumferential direction are formed in the side surface portion of the second member 32 arranged inside. The second member 32 is arranged such that these through holes 321 are shifted by 45 degrees in the circumferential direction with respect to the through holes 311 and 312 formed on the side surfaces of the first member 31 respectively. Is done.

  5 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 5, the first supply pipe 21 of the injector 20 provided in the first annular portion 331 perpendicular to the axis X is disposed upstream of the apex portion of the first member 31. . For this reason, the second supply pipe 22 provided extending from the first supply pipe 21 to the downstream side in the axis X direction is provided from the upstream side of the top part of the first member 31, and the top part of the second member 32. It extends to the downstream side.

  The second supply pipe 22 is formed with a first injection port, a second injection port, and a third injection port as a plurality of reducing agent injection ports in the direction of the axis X, and the tip of the second supply tube 22 is closed. ing. For this reason, the reducing agent passes through the through holes formed in the respective apex portions of the first member 31 and the second member 32, more specifically, through the second supply pipe 22 inserted through the through holes. The exhaust gas is supplied into the exhaust gas from a plurality of reducing agent injection ports.

6 is a cross-sectional view showing the configuration of the injector 20, wherein (a) is a cross-sectional view taken along the line BB of FIG. 5, (b) is a cross-sectional view taken along the line CC of FIG. FIG. 6 is a cross-sectional view taken along the line DD of FIG. As shown in FIG. 6A, three injections arranged at intervals of 120 degrees in the circumferential direction in a cross-sectional view at a position upstream of the apex of the first member 31 in the second supply pipe 22. A first injection port 221 comprising a mouth is formed. A reducing agent is injected from the first injection ports 221 to the outside of the first member 31.
As shown in FIG. 5, a gap is formed at the outer peripheral tip portion of the first member 31 with the inner wall surface of the cylindrical portion 333 constituting the case member 33, and is injected outside the first member 31. The reduced reducing agent flows from the gap to the downstream side.

  Moreover, as shown in FIG.6 (b), in the position of the 1st member 31 and the 2nd member 32 among the 2nd supply pipe | tubes 22, it is three injections arrange | positioned at 120 degree intervals in the circumferential direction by sectional view. A second injection port 222 composed of a mouth is formed. These second injection holes 222 are formed so as to be shifted by 60 degrees in the circumferential direction in a cross-sectional view with respect to the first injection holes 221 described above. A reducing agent is injected into the gap between the first member 31 and the second member 32 from these second injection ports 222. More specifically, the reducing agent is injected from these second injection ports 222 toward the inner wall surface of the first member 31.

Further, as shown in FIG. 6C, the second supply pipe 22 is disposed at a position downstream of the apex portion of the second member 32 at intervals of 90 degrees in the circumferential direction in a cross-sectional view. A third injection port 223 composed of two injection ports is formed. A reducing agent is injected into the second member 32 from these third injection ports 223. More specifically, the reducing agent is injected from these third injection ports 223 toward the inner wall surface of the second member 32.
Note that these third injection ports 223 are formed with a larger diameter than the first injection port 221 and the second injection port 222 described above. As a result, more reducing agent is injected from the third injection ports 223 into the second member 32.

The flow of exhaust and reducing agent in the mixer 3 having the above configuration will be described with reference to FIG.
FIG. 7 is a cross-sectional view showing the flow of exhaust and reducing agent in the mixer 3 according to this embodiment. Here, FIG. 7 is a cross-sectional view taken along the line AA of FIG. 3 as in FIG. Moreover, in FIG. 7, the solid line arrow schematically shows the flow direction of the exhaust gas, and the broken line arrow schematically shows the flow direction of the reducing agent.

First, as indicated by solid line arrows in FIG. 7, the exhaust gas flowing into the mixer 3 from the upstream side flows along the outer wall surface of the first member 31. At this time, the reducing agent injected from the first injection port 221 to the outside of the first member 31 is mixed with the exhaust gas flowing along the outer wall surface of the first member 31.
Part of the exhaust gas mixed with the reducing agent passes through the four through holes 311 and 312 formed on the side surface of the first member 31, respectively, and between the first member 31 and the second member 32. It flows into the gap. Further, the exhaust gas that flows along the outer wall surface of the first member 31 and reaches the outer peripheral tip portion of the first member 31 is formed between the outer peripheral tip portion and the inner wall surface of the cylindrical portion 333 constituting the case member 33. It flows downstream through the gap formed between them.

  Next, the reducing agent injected from the second injection port 222 into the gap between the first member 31 and the second member 32 passes through the through holes 311 and 312, and reaches the first member 31 and the second member 32. It is mixed with the exhaust gas flowing into the gap between them. The exhaust gas further mixed with the reducing agent in this way flows along the outer wall surface of the second member 32, and a part thereof passes through the four through holes 321 formed in the side surface portion of the second member 32. Then, it flows into the inside of the second member 32. Further, the exhaust gas that flows along the outer wall surface of the second member 32 and reaches the outer peripheral tip of the second member 32 flows from the outer peripheral tip to the downstream side.

  Next, the reducing agent injected from the third injection port 223 to the inside of the second member 32 is mixed with the exhaust gas that has passed through the through-hole 321 and flowed into the inside of the second member 32. At this time, the flow of the reducing agent is directed to the central portion in the radial direction of the exhaust pipe 11 by the exhaust gas that has passed through the through-hole 321 and flowed into the second member 32.

According to the exhaust emission control device according to the present embodiment having the above configuration, the following effects are exhibited.
In the present embodiment, the mixer 3 is configured by the first member 31 and the second member 32 that have a bottomless, hollow, substantially conical shape that increases in diameter toward the downstream side and have different diameters. Specifically, the second member 32 having a diameter smaller than that of the first member 31 is disposed on the inner side of the first member 31 with a gap between the inner wall surface of the first member 31 and the same axis X. Both members were arranged so that Furthermore, a through hole was formed at each apex of both members, and a reducing agent was supplied from above the axis X through these through holes.
Thereby, the reducing agent supplied through the through-holes formed in the respective apex portions flows into the exhaust gas by the exhaust gas flowing downstream through the substantially conical first member 31 and the second member 32. Spreading is promoted. Therefore, according to the present embodiment, the reducing agent and the exhaust gas can be uniformly mixed at a shorter distance than conventional.

  In the present embodiment, four through holes 321 are formed in the side surface portion of the second member 32 disposed on the inner side. As a result, the reducing agent supplied through each apex portion is promoted to diffuse into the exhaust gas by the exhaust gas flowing from the four through holes 321 formed in the side surface portion of the second member 32. Therefore, according to the present embodiment, the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than conventional. Further, the pressure loss can be further reduced by forming the four through holes 321 in the side surface portion of the second member 32.

  In the present embodiment, four through holes 311 and four through holes 312 are formed on the side surface of the first member 31 arranged on the outside. As a result, the reducing agent supplied via each apex portion flows in through holes 311 and 312 formed in the side surface portion of the first member 31 and is exhausted through the second member 32 to the downstream side. , Diffusion into the exhaust is promoted. Therefore, according to the present embodiment, the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than conventional. Further, the pressure loss can be further reduced by forming the through holes 311 and 312 in the side surface portion of the first member 31.

Moreover, in this embodiment, when the through-hole 321 formed in the side part of the 2nd member 32 and the through-holes 311 and 312 formed in the side part of the 1st member 31 are seen from the downstream of the axis X direction, it mutually Both members were arranged so as to be displaced in the circumferential direction.
Here, when the through holes 321 formed in the side surface portion of the second member 32 and the through holes 311 and 312 formed in the side surface portion of the first member 31 are on a straight line along the axis X direction, the exhaust is As a result of flowing on the straight line, the inflow of exhaust gas between the two members cannot be promoted, and the effect of promoting the diffusion of the reducing agent by providing the through holes in the side surfaces of the two members cannot be sufficiently obtained. On the other hand, according to this embodiment, since the through holes formed in the side surface portions of both members are displaced from each other in the circumferential direction when viewed from the downstream side in the axis X direction, between the two members. Inflow of exhaust can be promoted. Therefore, diffusion of the reducing agent into the exhaust can be promoted, and the reducing agent and the exhaust can be uniformly mixed at a shorter distance than before.

  In the present embodiment, the through hole 312 in the side surface portion of the first member 31 disposed on the outside is also formed at a position that does not overlap the second member 32 when viewed from the downstream side in the axis X direction. Thus, the exhaust gas flowing between the two members is directed to the center in the radial direction of the exhaust pipe 11 by the exhaust gas flowing from the through hole 312 of the side surface portion of the first member 31 formed at a position not overlapping the second member 32. Can be made. Therefore, according to the present embodiment, the reducing agent uniformly mixed in the exhaust gas can be efficiently supplied to the downstream exhaust gas purification means.

In the present embodiment, the reducing agent is supplied to the inside of the second member 32, the gap between the first member 31 and the second member 32, and the outside of the first member. In addition, a gap was formed between the inner wall surface of the cylindrical portion 333 of the case member 33 that accommodates the first member 31 and the second member 32 at the outer peripheral tip of the first member 31.
Thereby, since the reducing agent can be supplied to the inside of the second member 32, the gap between the two members, and the outside of the first member 31 from the axis X through the through-holes of the respective apex portions, the reducing agent into the exhaust gas can be supplied. Diffusion can be promoted, and the reducing agent and exhaust can be mixed more uniformly at a shorter distance than before.

In the present embodiment, the second supply pipe 22 extending along the axis X direction from the upstream side of the first member 31 to the downstream side of the second member 32 is provided. The through holes formed at the vertices of both members were inserted. The second supply pipe 22 has a first injection port 221 for injecting a reducing agent to the outside of the first member 31, a second injection port 222 for injecting a reducing agent into the gap between the two members, and a second member 32. And a third injection port 223 for injecting the reducing agent.
Thus, the reducing agent can be supplied to the inside of the second member 32, the gap between the two members, and the outside of the first member 31, and the supplied reducing agent flows into the downstream side through both of the substantially conical members. Can diffuse efficiently into the exhaust. Therefore, according to the present embodiment, the reducing agent and the exhaust gas can be mixed more uniformly at a shorter distance than in the past.

In the present embodiment, as the reducing agent, it was used as the mixed gas to the NH ₃ gas or the liquid reducing agent. Thereby, the above-mentioned effect is reliably show | played by supplying a gaseous reducing agent to a mixer.

[Second Embodiment]
Exhaust gas purification apparatus 10A according to the second embodiment of the present invention has the same configuration except that the configuration of mixer 3A and the configuration of injector 20A are different from those of the first embodiment.
FIG. 8 is a diagram illustrating the configuration of the mixer 3A and the injector 20A according to the second embodiment of the present invention and the flow of exhaust gas and reducing agent. Here, FIG. 8 is a cross-sectional view cut in the same direction as FIGS. 5 and 7. Moreover, in FIG. 8, the solid line arrow schematically shows the flow direction of the exhaust gas, and the broken line arrow schematically shows the flow direction of the reducing agent.

As shown in FIG. 8, in the present embodiment, the configuration of the second supply pipe 22A of the injector 20A is different from that of the first embodiment. Specifically, the second supply pipe 22 </ b> A extends only to a position upstream from the apex of the first member 31. That is, the second supply pipe 22A is not inserted into the through hole 310 formed at the apex of the first member 31 and the through hole 320A formed at the apex of the second member 32A. 310 and 320A are exposed.
The tip of the injector 20A is open, and the reducing agent is injected from the opening 220 toward the downstream side in the axis X direction.

  Further, the configuration of the second member 32 of the mixer 3A is different from that of the first embodiment. Specifically, a through hole 320A formed at the apex of the second member 32 is formed with a smaller diameter than in the first embodiment. As a result, a part of the reducing agent that has flowed from the through hole 310 formed at the apex portion of the first member 31 is restricted so as to flow along the outer wall surface of the second member 32.

The flow of the exhaust gas and the reducing agent in the mixer 3A having the above configuration will be described with reference to FIG.
First, as indicated by solid line arrows in FIG. 8, the exhaust gas flowing into the mixer 3 </ b> A from the upstream side flows along the outer wall surface of the first member 31. At this time, the reducing agent injected from the opening 220 at the tip of the second supply pipe 22 </ b> A passes through the through-hole 310 formed at the apex of the first member 31, and a part of the reducing agent is outside the first member 31. It flows with the exhaust along the wall and is mixed.
Part of the exhaust gas mixed with the reducing agent passes through the four through holes 311 and 312 formed on the side surface of the first member 31, respectively, and between the first member 31 and the second member 32. It flows into the gap. Further, the exhaust gas that flows along the outer wall surface of the first member 31 and reaches the outer peripheral tip portion of the first member 31 is formed between the outer peripheral tip portion and the inner wall surface of the cylindrical portion 333 constituting the case member 33. It flows downstream through the gap formed between them.

Next, the reducing agent that has passed through the through hole 310 formed at the apex portion of the first member 31 passes through the through hole 320 </ b> A formed at the apex portion of the second member 32, and a part of the reducing agent It flows along the outer wall surface and is mixed with the exhaust gas that has passed through the through holes 311 and 312 formed in the side surface of the first member 31. At this time, since the through hole 320 </ b> A formed at the apex of the second member 32 has a smaller diameter than the through hole 310 formed at the apex of the first member 31, more reducing agent is added to the second member 32. It is directed in a direction along the outer wall surface.
A part of the exhaust gas flowing along the outer wall surface of the second member 32 passes through the four through holes 321 formed in the side surface portion of the second member 32 and flows into the second member 32. Further, the exhaust gas that flows along the outer wall surface of the second member 32 and reaches the outer peripheral tip of the second member 32 flows from the outer peripheral tip to the downstream side.

  Next, the reducing agent that has passed through the through hole 320 </ b> A formed at the apex of the second member 32 is mixed with the exhaust gas that has passed through the through hole 321 and has flowed into the second member 32. At this time, the flow of the reducing agent is directed to the central portion in the radial direction of the exhaust pipe 11 by the exhaust gas that has passed through the through-hole 321 and flowed into the second member 32.

  According to the exhaust gas purification apparatus 10A according to the second embodiment having the above configuration, the same effects as the exhaust gas purification apparatus 10 according to the first embodiment are exhibited. In particular, by setting the diameter of the through hole formed in the apex portion of the second member 32 smaller than the diameter of the through hole formed in the apex portion of the first member 31, the reducing agent supplied from the axis X A part can be efficiently supplied to the gap between the two members. Therefore, the diffusion of the reducing agent into the exhaust can be further promoted, and the reducing agent and the exhaust can be mixed more uniformly at a shorter distance than in the past.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, the number and arrangement of the through holes formed in the side surface of the first member 31 and the side surface of the second member 32 can be changed as appropriate.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[Example 1]
An exhaust emission control device according to the first embodiment described above was produced.

[Comparative Example 1]
An exhaust emission control device including a mixer 3B and an injector 20B according to Comparative Example 1 as shown in FIG. 9 was produced. The mixer 3B according to the comparative example 1 includes a cylindrical case member 33B that increases in diameter toward the downstream side, and four fins 31B that are fixed in the case member 33B by the injector 20B. The four fins 31B are provided so that the longitudinal directions of adjacent fins are orthogonal to each other, and each has a shape bent toward the downstream side at a substantially central portion in the longitudinal direction.
The injector 20B includes two supply pipes that extend in the radial direction of the exhaust pipe and are orthogonal to each other, and the tip ends of the supply pipes are connected to the fins 31B. Moreover, the injection port which opens toward the downstream is formed in the front-end | tip part of each supply pipe | tube, and a reducing agent is injected from these injection ports.

[Comparative Example 2]
An exhaust emission control device including a mixer 3C and an injector 20C according to Comparative Example 2 as shown in FIG. 10 was produced. The mixer 3 </ b> C according to the comparative example 2 includes fins 31 </ b> C having a substantially rhombus shape bent toward the downstream side with a folding axis orthogonal to the exhaust flow direction. A plurality of slits 32C are formed in the fin 31C.
The injector 20C is provided on the above-described folding shaft, and includes a supply pipe connected to the fin 31C from a substantially central portion of the folding shaft. The leading end of the supply pipe is opened, and the reducing agent is injected from the opening into the fin 31C.

[Evaluation]
The UI when the exhaust gas purification devices manufactured in Example 1 and Comparative Examples 1 and 2 are arranged in the exhaust pipe of the diesel engine section, and the exhaust gas is allowed to flow in under a predetermined operating condition and a predetermined amount of reducing agent is supplied. The value was measured. Here, the UI value is used as an index of the uniformity of the flow, and was obtained by calculation using the following formula (1).
[Equation 1]

UI = 1−Σ {| Vi−Vave | × Si / (2 × Vave × S)} Expression (1)

In the above formula (1), Vi represents the flow velocity (NH ₃ concentration) in each area obtained by dividing the channel cross section, and Vave represents the average flow velocity (cross section NH ₃ concentration) in the entire channel cross section. Si represents the area of each area, and S represents the total area of the flow path cross section.

FIG. 11 is a diagram illustrating UI values of Example 1, Comparative Example 1, and Comparative Example 2. In FIG. 11, RP1 means the position closest to the tip of the injector, and means that RP2 and RP3 move away from the tip of the injector in this order.
As shown in FIG. 11, it was found that Example 1 can obtain a higher UI value than Comparative Examples 1 and 2 not only in RP1, which is a short distance from the tip of the injector, but also in both RP2 and RP3. . From this result, it was confirmed that according to the exhaust gas purification apparatus of the present invention, the reducing agent and the exhaust gas can be uniformly mixed at a shorter distance than before.

Further, for Example 1 and Comparative Example 2, the relationship between the exhaust flow rate and the back pressure was examined. FIG. 12 is a diagram illustrating the relationship between the exhaust flow rate and the back pressure in Example 1 and Comparative Example 2.
As shown in FIG. 12, in the comparative example 2, since the fin 31C has a shape that easily hinders the flow of exhaust gas, the back pressure becomes very high as the exhaust gas flow rate increases. On the other hand, in Example 1, it was found that the back pressure hardly increased even when the exhaust gas flow rate was increased. From this result, it was confirmed that according to the exhaust gas purification apparatus of the present invention, the pressure loss can be reduced as compared with the prior art.

DESCRIPTION OF SYMBOLS 1 ... Upstream catalytic converter 2 ... Reducing agent supply apparatus (reducing agent supply means)
3 ... Mixer 4 ... Downstream catalytic converter (exhaust purification means)
10 ... Exhaust gas purification device 11 ... Exhaust pipe (exhaust passage)
20 ... Injector (reducing agent supply means)
22 ... Second supply pipe (reducing agent supply pipe)
DESCRIPTION OF SYMBOLS 31 ... 1st member 32 ... 2nd member 33 ... Case member 221 ... 1st injection port 222 ... 2nd injection port 223 ... 3rd injection port 310 ... Through-hole (through-hole formed in the vertex part of the 1st member)
311, 312... Through hole (through hole formed in the side surface of the first member)
321 ... Through hole (through hole formed in the side surface of the second member)
320 ... through hole (through hole formed at the apex of the second member)

Claims (10)

A reducing agent supply means provided in the exhaust passage of the internal combustion engine for supplying the reducing agent into the exhaust passage;
An exhaust purification means that is provided in an exhaust passage downstream of the reducing agent supply means and purifies exhaust gas by the reducing agent supplied by the reducing agent supply means;
An exhaust purification device for an internal combustion engine, comprising: a mixer provided in an exhaust passage between the reducing agent supply means and the exhaust purification means, and a mixer that mixes the reducing agent supplied by the reducing agent supply means and exhaust gas. ,
The mixer has a gap between a first member having a bottomless, hollow, substantially conical shape that expands in diameter toward the downstream side, and an inner wall surface of the first member inside the first member. A second member having a substantially conical shape with a diameter smaller than that of the first member, the bottom member being hollow and expanding toward the downstream side.
The first member and the second member are provided on the same axis line, and a through hole is formed at each apex portion,
The exhaust gas purifying apparatus for an internal combustion engine, wherein the reducing agent supply means supplies the reducing agent from above the axis via the through hole.   The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein at least one through hole is formed in a side surface portion of the second member.   The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2, wherein at least one through hole is formed in a side surface portion of the first member.   The through hole formed in the side surface portion of the second member and the through hole formed in the side surface portion of the first member are arranged so as to be shifted from each other in the circumferential direction when viewed from the downstream side in the axial direction. The exhaust emission control device for an internal combustion engine according to claim 3, wherein the exhaust gas purification device is an internal combustion engine.   The through-hole formed in the side surface portion of the first member includes a through-hole formed at a position that does not overlap the second member when viewed from the downstream side in the axial direction. Item 5. An exhaust purification device for an internal combustion engine according to Item 3 or 4.   The reducing agent supply means is configured to supply a reducing agent to a plurality of locations, and supplies the reducing agent to at least the inside of the second member and the gap between the first member and the second member. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 5, characterized in that: The reducing agent supply means is configured to supply a reducing agent to a plurality of locations, and supplies the reducing agent to at least the inside of the second member and the outside of the first member,
The clearance gap is formed in the outer peripheral front-end | tip part of the said 1st member between the inner wall surface of the said exhaust passage or the inner wall surface of the case member which accommodates the said 1st member and the 2nd member. Item 7. An exhaust emission control device for an internal combustion engine according to any one of Items 1 to 6.   The diameter of the through hole formed in the vertex part of the second member is smaller than the diameter of the through hole formed in the vertex part of the first member. An exhaust purification device for an internal combustion engine. The reducing agent supply means extends along the axial direction from the upstream side of the first member to the downstream side of the second member, and includes each of the first member and the second member. It is configured to include a reducing agent supply pipe inserted into each through hole formed at the apex,
The reducing agent supply pipe has a plurality of reducing agent injection ports in the axial direction;
The reducing agent injection port includes a first injection port for injecting a reducing agent to the outside of the first member, a second injection port for injecting a reducing agent into a gap between the first member and the second member, and the first The exhaust emission control device for an internal combustion engine according to any one of claims 2 to 8, further comprising a third injection port for injecting the reducing agent inside the two members. The exhaust purification device for an internal combustion engine according to any one of claims 1 to 9, wherein the reducing agent is a mixture of NH ₃ gas or liquid reducing agent with gas.

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