JP2009041371A - Exhaust emission control device and mixer unit of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device and a mixer unit in which a reducer is efficiently mixed and diffused in exhaust gas, and the distribution of the spray of the passing reducer is brought into a steady state, and the reducer is allowed to flow to the inlet of a reduction catalyst. <P>SOLUTION: This exhaust emission control device of an internal combustion engine comprises the reduction catalyst disposed in the exhaust passage of the internal combustion engine, and a reducer injection part for injecting the reducer in the exhaust passage on the upstream side of the reduction catalyst. This mixer unit for mixing and diffusing the reducer and the exhaust gas is disposed on the upstream side of the reduction catalyst and the downstream side of the injection position of a reducer injection part. The mixer unit comprises a mixer body part formed by arranging a plurality of wire meshes in the flowing direction of the exhaust gas and a diffusing member attached to the reduction catalyst side of the mixer body part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust purification device for reducing and purifying nitrogen oxide in exhaust gas discharged from an internal combustion engine, and a mixer unit used in such an exhaust purification device.

Conventionally, the nitrogen oxides contained in the exhaust gas discharged from an internal combustion engine (hereinafter, referred to as NO _X.) To remove the exhaust gas purification device provided with a selective reduction catalyst and the injection device of the liquid reducing agent Are known. Such an exhaust purification device sprays a liquid reducing agent, such as an aqueous urea solution, into the exhaust gas upstream of the reduction catalyst, mixes it, flows it into the reduction catalyst, and hydrolyzes the liquid reducing agent in the reduction catalyst. Nitrogen oxide is purified by a reduction reaction between ammonia and nitrogen oxide.

  As a device for supplying the reducing agent into the exhaust passage, the compressed air is mixed with the liquid reducing agent in the mixing chamber and atomized and then supplied from a nozzle in the exhaust pipe, or a so-called air assist type device or an exhaust pipe. There is an injection-type device that sprays a reducing agent from an injector into an exhaust passage by pumping a liquid reducing agent to an attached injector and opening and closing a flow path leading to an injection hole. Among these, in the type in which the reducing agent is sprayed using an injector, the particles of the reducing agent are not easily diffused, and the spray distribution flowing into the inlet surface of the reduction catalyst is easily biased.

  When the sprayed reducing agent flowed in a biased distribution toward the inlet of the reduction catalyst, it was not used for the reduction reaction of nitrogen oxides in the ammonia produced in the region where the amount of reducing agent inflow was large. In a region where ammonia is released into the atmosphere as it is and the amount of reducing agent inflow is small, there is a risk that the nitrogen oxides in the exhaust gas will not be sufficiently reduced and will be released into the atmosphere as they are. For this reason, a mixer is disposed in the exhaust passage so that the distribution of the liquid reducing agent reaching the reduction catalyst is uniform.

  For example, as shown in FIG. 10, the selective reduction catalyst 324 provided in the exhaust pipe 316 of the engine 311 and the selective reduction catalyst 324 provided in the exhaust pipe 316 upstream of the exhaust gas from the selective reduction catalyst 324. An exhaust purification device including a liquid injection nozzle 329 capable of injecting a urea-based liquid 332, and a mixer 351 configured to be able to mix the liquid 332 injected from the liquid injection nozzle 329 with exhaust gas is provided with the liquid injection nozzle 329. Provided in the exhaust pipe 316 between the selective catalytic reduction catalyst 324, the mixer 351 blocks the passage of the exhaust gas inside the cylinder body 352a and the mixer main body 352 having the cylinder part 352a capable of passing the exhaust gas in the axial direction. A plurality of partition plates 353 provided in the mixer main body 352 at predetermined intervals and each having a plurality of gas holes formed therein. It is formed so as not to overlap in the axial direction of the adjacent plurality of gas holes formed in the partition plate 353 and the cylindrical portion 352a exhaust gas purification device is disclosed (see Patent Document 1).

JP 2003-232218 A (Claims Fig. 1)

However, in the case of the configuration of the exhaust gas purifying apparatus described in Patent Document 1, a partition plate in which a plurality of gas holes is formed is used, and a plane portion where a portion other than the gas holes intersects the flow direction of the exhaust gas; It has become. Therefore, the reducing agent collides with the flat part and spreads and adheres in a flat shape. The attached reducing agent is less likely to be atomized, and liquid dripping may occur when it cannot evaporate. Therefore, it becomes difficult to diffuse the reducing agent mixed exhaust gas and uniformly flow it into the reduction catalyst, which may reduce the NO _x reduction efficiency.

  Accordingly, the inventors of the present invention have made diligent efforts to use a mixer unit including a mixer main body portion in which a plurality of wire meshes are arranged, and a diffusion member disposed on the reduction catalyst side of the mixer main body portion. The present invention has been completed by finding that such problems can be solved. That is, an object of the present invention is to provide an exhaust purification device for an internal combustion engine that can efficiently diffuse the reducing agent mixed exhaust gas through the mixer unit and uniformly flow into the inlet surface of the reduction catalyst. To do. Another object of the present invention is to provide a mixer unit used in such an exhaust purification device.

  According to the present invention, the exhaust gas of an internal combustion engine provided with a reduction catalyst disposed in the exhaust passage of the internal combustion engine and a reducing agent injection unit for injecting the reducing agent into the exhaust passage on the upstream side of the reduction catalyst. A purification device, a mixer unit for mixing and diffusing the reducing agent and the exhaust gas is arranged upstream of the reduction catalyst and downstream of the injection position by the reducing agent injection unit. An exhaust gas purification apparatus for an internal combustion engine, comprising: a mixer main body portion including a wire mesh arranged in a plurality of exhaust gas flow directions; and a diffusion member disposed on a reduction catalyst side of the mixer main body portion. Provided and can solve the above-mentioned problems.

  Further, when configuring the exhaust gas purification apparatus for an internal combustion engine of the present invention, the mixer body is configured by fixing a plurality of mesh plates each having a wire mesh held by a fixing plate to each other. It is preferable that a gap is formed between the wire meshes by fixing the fixing plates.

  Further, in configuring the exhaust gas purification apparatus for an internal combustion engine of the present invention, when the plurality of wire meshes constituting the mixer main body portion are viewed in the flow direction of the exhaust gas, at least one wire mesh opening has other It is preferable that the position is shifted from the position of the opening of the wire mesh.

Another aspect of the present invention is used in an exhaust gas purification apparatus for an internal combustion engine that reduces and purifies NO _{x in} exhaust gas using a reducing agent, and mixes and diffuses the reducing agent and exhaust gas supplied into the exhaust passage. A mixer unit including a wire body arranged in the exhaust gas flow direction, and a diffusion member disposed on the reduction catalyst side of the mixer body. It is a mixer unit.

According to the exhaust gas purification apparatus for an internal combustion engine of the present invention, since the mixer main body portion is configured using a plurality of wire meshes, the reducing agent spray collision surface becomes a curved surface, so that the reducing agent is planar. It is prevented from spreading and adhering. That is, the reducing agent that has collided with the wire mesh spreads in a liquid film shape along the curved surface of the wire mesh, and then is easily sheared when leaving the wire mesh, thereby promoting the formation of fine particles. In addition, exhaust gas that passes through the wire mesh generates strong vortex turbulence and increases the flow velocity, so that the reducing agent is affected by the exhaust gas flow and its evaporability is improved. Become.
Moreover, since the atomized reducing agent spray that has passed through the mixer main body is diffused into the exhaust passage by the diffusion member, it can be made to uniformly flow into the inlet surface of the reduction catalyst. Therefore, NO _x can be reduced using the entire surface of the reduction catalyst, and the exhaust gas can be efficiently purified.

  Further, in the exhaust gas purification apparatus for an internal combustion engine of the present invention, by configuring the mixer body using a mesh plate that holds the wire mesh with a fixing plate, the adjacent wire meshes are prevented from contacting each other, and the wire mesh Atomization by passing through can be efficiently performed.

  Further, in the exhaust gas purification apparatus for an internal combustion engine of the present invention, the mixer main body portion is moved by rotating at least one wire mesh among a plurality of wire meshes constituting the mixer main body portion and shifting the position of the opening. The collision frequency of the reducing agent that passes through can be improved, and the reducing agent can be made into fine particles efficiently.

Moreover, according to the mixer unit of the present invention, since the mixer main body portion is configured by using a plurality of wire meshes, the reducing agent spray collision surface becomes a curved surface, so that the reducing agent spreads in a planar shape. It is prevented from adhering. That is, the reducing agent that has collided with the wire mesh spreads in a liquid film shape along the curved surface of the wire mesh, and then is easily sheared when leaving the wire mesh, thereby promoting the formation of fine particles. In addition, exhaust gas that passes through the wire mesh generates strong vortex turbulence and increases the flow velocity, so that the reducing agent is affected by the exhaust gas flow and its evaporability is improved. Become.
Moreover, since the atomized reducing agent spray that has passed through the mixer main body is diffused into the exhaust passage by the diffusion member, it can be made to uniformly flow into the inlet surface of the reduction catalyst. Therefore, NO _x can be reduced using the entire surface of the reduction catalyst, and the exhaust gas can be efficiently purified.

DESCRIPTION OF EMBODIMENTS Embodiments relating to an exhaust gas purification apparatus and a mixer unit for an internal combustion engine according to the present invention will be specifically described below with reference to the drawings. However, this embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In the drawings, the same members are denoted by the same reference numerals, and description thereof is omitted as appropriate.

1. FIG. 1 is a cross-sectional view showing a configuration of an exhaust gas purification device (hereinafter simply referred to as “exhaust gas purification device”) 10 for an internal combustion engine including a mixer unit 11 according to an embodiment of the present invention.
The exhaust purification apparatus 10 according to the present embodiment includes an internal combustion engine 5 that discharges exhaust gas, an exhaust pipe 25 connected to the internal combustion engine 5, a reduction catalyst 13 connected in the middle of the exhaust pipe 25, and a reduction catalyst 13. And a reducing agent supply device 30 for injecting the reducing agent into the exhaust passage on the upstream side. An upstream oxidation catalyst 19 and a downstream oxidation catalyst 17 are arranged on the upstream side and the downstream side of the reduction catalyst 13, respectively.

Of these, the internal combustion engine 5 is a diesel engine or a gasoline engine is typically be targeted diesel engine purification degree of PM and NO _X in the exhaust gas at present is a problem is suitable.

The reducing agent supply device 30 includes a reducing agent storage tank 31, a pump 33 that pumps the reducing agent in the storage tank 31, and an injector 35 that injects the reducing agent into the exhaust passage. The pump 33 is, for example, an electric pump, and is controlled so that the pressure in the reducing agent supply path 37 is maintained at a predetermined pressure. The injector 35 is composed of, for example, an ON-OFF valve that controls ON / OFF of the valve opening by DUTY control. The injector 35 is provided in the exhaust pipe 25 on the upstream side of the reduction catalyst 13 so that the injection hole 35a is desired in the exhaust passage. It is attached.
The amount of reducing agent injected by the reducing agent supply device 30, the rotational speed and the load state of the internal combustion engine 5 is determined in accordance with the discharge amount of NO _X is estimated based on the fuel injection quantity, etc., in the injection amount Accordingly, the DUTY control of the injector 35 is performed.

As the reducing agent used, an aqueous urea solution is typical. For example, when this urea aqueous solution is used, urea (NH ₃ ) is generated by hydrolysis of urea injected into the exhaust passage by heat in the exhaust gas, and this NH ₃ and NO in the exhaust gas are generated. _{When X} (NO or NO ₂ ) reacts in the reduction catalyst, NO _X is reduced, decomposed into nitrogen (N ₂ ) and water (H ₂ O), and discharged.
In addition to this, a material capable of reducing NO _x such as unburned fuel (HC) can be used as the liquid reducing agent.

The reduction catalyst 13 used in the exhaust purification apparatus 10 of this embodiment is a selective reduction type reduction catalyst that selectively reduces and purifies NO _x contained in exhaust gas. The reduction catalyst 13 is a known catalyst, for example, a porous carrier, strontium or barium as an active component, an alkaline earth metal such as magnesium, a rare earth metal such as cerium and lanthanum, or a noble metal such as platinum and rhodium. Etc. can be used.

  Further, on the upstream side of the reduction catalyst 13 and on the downstream side of the injection position of the injector 35, a mixer unit 11 to be described later is attached so as to be sandwiched between exhaust pipes. The above-described injector 35 is attached with its injection direction determined so that the injected reducing agent collides with the mixer unit 11.

Further, a downstream side oxidation catalyst 17 is disposed downstream of the reduction catalyst 13, and it is assumed that ammonia generated by hydrolysis of the urea aqueous solution as the reducing agent slips and passes through the reduction catalyst 13 as it is. even, thereby making it possible to oxidize to release in the low NO ₂ relatively hazardous by the downstream oxidation catalyst 17.
Further, an upstream side oxidation catalyst 19 is disposed upstream of the reduction catalyst 13, and NO contained in the exhaust gas is oxidized to generate NO _{2 that} is more easily reacted with the reducing agent, and carbon monoxide (CO ) Is oxidized to generate carbon dioxide (CO ₂ ), and the ratio tends to cause a reduction reaction. The oxidation heat generated when these oxidation reactions occur can be caused to flow into a mixer unit 11 and a reduction catalyst 13 which will be described later, and the reduction catalyst 13 can be heated and activated while the mixer unit 11 is heated. .
As the upstream side oxidation catalyst 19 and the downstream side oxidation catalyst 17, a known catalyst, for example, a catalyst in which platinum is supported on alumina and a rare earth element such as cerium added thereto can be used.

2. Next, the mixer unit 11 provided in the exhaust emission control device 10 of the present embodiment will be described in detail. 2A is a side view showing an example of the configuration of the mixer unit 11, and FIG. 2B is a front view of the mixer unit 11 viewed from the upstream side (exhaust gas inflow side). (C) is the back front view which looked at the mixer unit 11 from the downstream (exhaust gas outflow side). 3 is an exploded perspective view of the mixer unit 11 for each component. FIG. 4 is an exploded view of the mesh plate 51 constituting the mixer body 52 of the mixer unit 11 for each component. It is a disassembled perspective view.

  The mixer unit 11 is for atomizing the spray of the injected reducing agent and mixing and diffusing it into the exhaust gas. The mixer unit 11 includes a mixer body 52 and a diffusion member 53. Each member of the mixer unit 11 is fixed by being welded to each other, and since the mixer unit 11 is attached so as to be sandwiched between the exhaust pipes, airtightness and strength are ensured. It has come to be.

In addition, the mixer main body 52 is configured by welding and fixing a plurality (five in the illustrated example) of mesh plates 51a to 51e. As shown in FIG. 4, each of the mesh plates 51 a to 51 e includes a wire mesh 54 and two fixing plates 55 that hold the wire mesh 54.
The wire mesh 54 used here is a mesh-like member configured using a metallic wire, and the roughness thereof is, for example, a diameter of the wire constituting the mesh of 0.3 to 0.8 mm, the number of meshes A wire mesh having 4 to 15 (number of eyes per inch) and a space ratio (opening ratio) of 70 to 90% can be used. However, these numerical values are not limited. Considering the exhaust gas flow rate calculated by CFD (fluid numerical calculation) or the like, considering the pressure loss of the exhaust gas or the degree of diffusion of the reducing agent particles. It can be set appropriately.
The fixing plate 55 is a ring-shaped member having an opening 55a at the center, and a groove 55b in which the wire mesh 54 is disposed is provided around the opening 55a on one surface. ing. Then, the two fixing plates 55 are overlapped so that the groove portions 55b face each other, and the two fixing plates 55 are fixed by welding so that the wire mesh 54 is sandwiched in the groove portions.

In the case of the mesh plate configured as described above, a gap is formed without contacting adjacent wire meshes 54 by welding and fixing the fixing plates of adjacent mesh plates to each other as shown in FIG. Can be arranged.
That is, when the wire meshes 54 are arranged so as to be in contact with each other, as shown in FIG. 6, a plurality of passages P are formed in the mixer main body 52, and exhausted by passing through the wire mesh 54. This is because gas turbulence and atomization due to shear may be insufficient. Furthermore, when the position of the opening part of the wire mesh 54 is shifted as will be described later, if the wire meshes 54 are in contact with each other, the opening part of the mesh is blocked. This is because the pressure loss of the exhaust gas passing through the main body 52 may increase.

Further, in the example of the present embodiment, mesh plates 51a to 51e configured to sandwich the wire mesh 54 between the two fixing plates 55 are used, but the configuration of the mixer body 52 is limited to such a configuration. It is not something.
For example, the wire mesh can be held by a single fixing plate, or a plurality of wire meshes can be held in one casing without using the fixing plate. .

Moreover, in the mixer main body part 52 of the mixer unit 11 of this embodiment, as shown to Fig.7 (a), several mesh plate 51a-51e which comprises the mixer main body part 52 is followed along the flow direction of exhaust gas. When viewed, the mesh openings are arranged so as to be rotated in the axial rotation direction so that the positions of the mesh openings are shifted. More specifically, the mesh plates 51a to 51e are arranged so as to be axially rotated by 15 degrees as they go downstream in the exhaust gas flow direction.
Therefore, when viewed along the flow direction of the exhaust gas, the position of the opening of the wire mesh 54 is shifted, and the frequency of the reducing agent passing through the mixer main body 52 colliding with the wire mesh 54 increases. ing. As a result, as compared with the case where the position of the opening is not shifted, atomization due to collision is promoted and diffusion is facilitated. In the configuration of the mixer main body 52 of the present embodiment, since a gap is formed between adjacent wire meshes 54, even if the position of the opening of the wire mesh 54 is shifted, Exhaust gas and reducing agent passages are secured so that there is no risk of pressure loss.

Various selections are possible for the shaft rotation angle of the mesh plate 51 constituting the mixer main body 52. For example, in the configuration of the mixer main body 52 shown in FIG. 7B, five mesh plates 51a to 51e are arranged along the exhaust gas flow direction, and are located on the most downstream side in the exhaust gas flow direction. Only the plate 51e is disposed by being rotated 45 degrees in the axial rotation direction. In addition to this, if at least one mesh plate is axially rotated and the opening is shifted, the frequency with which the reducing agent collides with the wire mesh can be increased.
Moreover, it can select suitably also about the number of the wire mesh which comprises a mixer main-body part.

Further, as for the distance between adjacent wire meshes 54, the smaller the distance, the greater the turbulence caused by the influence of the vortex generated when the exhaust gas passes through the plurality of wire meshes 54. Therefore, in order to atomize the reducing agent and facilitate mixing and diffusion with the exhaust gas, it is preferable to make the distance between the adjacent wire meshes 54 relatively small.
However, if the distance between the adjacent wire meshes 54 becomes excessively small, the eddy current generated when passing through each wire mesh 54 is weakened, or if the opening of the wire mesh 54 is shifted, the exhaust gas is It becomes difficult to pass through the mixer main body 52 and the pressure loss increases. That is, when the openings of the wire mesh 54 are coincident with each other, a plurality of passages are formed in the mixer main body 52 as a whole, and the formation of the vortex is weakened. When the portion is shifted, the opening of the wire mesh 54 is blocked by another wire mesh 54, and the pressure loss increases.

On the other hand, if the distance between adjacent wire meshes 54 is too large, the vortex generated by passing through each wire mesh 54 is likely to be rectified, and the disturbance of the exhaust gas flow is suppressed, making it difficult to atomize. There is.
Therefore, it is preferable to adjust the interval between the adjacent wire meshes 54 according to the flow of exhaust gas and the amount of reducing agent spray. In the case of the configuration of the mixer main body 52 of the present embodiment, the distance between the adjacent wire meshes 54 can be easily adjusted by changing the thickness of the fixing plate 55 that holds the wire mesh 54.

  2 and 3, a diffusion member 53 for diffusing the exhaust gas mixed with the atomized reducing agent spray is attached to the surface of the mixer main body 52 on the reduction catalyst side. Yes. The configuration of the diffusing member 53 is not particularly limited, and various forms are conceivable, but the diffusing member 53 provided in the mixer unit 11 of the present embodiment has a diffusing portion as shown in FIG. 61 and a support portion 62 are provided. Of these, the diffusing section 61 has a tapered shape that radially expands toward the reduction catalyst, and a plurality of tapered plates having different sizes are arranged concentrically, and each tapered plate is arranged. It is configured by being fixed by two support portions 62 assembled in a cross shape.

In addition to this, the configuration of the diffusing member 53 may be a configuration in which a spiral flat plate 61a radially extending toward the reduction catalyst is fixed by a support portion 62a, as shown in FIG. 8B. Further, as shown in FIG. 8C, the support portion 62b that supports the diffusion portion 61b can be changed from a flat plate to a round bar.
In addition, when the diffusing portion 61 having a shape radially extending toward the reduction catalyst is used, the spread angle does not need to be constant, and the angle can be changed in each portion.

  Moreover, in order to promote atomization of the reducing agent that passes through the mixer unit 11 and to facilitate diffusion into the exhaust gas, a heating device for heating the mixer body 52 and the diffusion member 53 can be provided. For example, by attaching a heating wire or a glow plug so as to be in contact with the mixer body 52 or the diffusion member 53, the spray of the reducing agent can be easily vaporized, and atomization can be promoted.

  Next, how the reducing agent passes through the mixer unit 11 shown in FIG. 1 will be described with reference to FIG.

  As described above, in the exhaust emission control device of the present embodiment, the injector is arranged such that the injection direction of the injector is directed toward the mixer unit 11, and the injected reducing agent proceeds toward the mixer unit 11. Yes. Therefore, the reducing agent is sprayed directly toward the mixer unit 11 and reliably collides with the wire mesh 54. If the injection range when the reducing agent to be injected reaches the mixer unit 11 is arranged so that it does not protrude outside the mixer unit 11, the atomization and diffusion effect of the reducing agent can be maximized. At the same time, it is possible to reduce the possibility that the reducing agent adheres to a portion other than the mixer unit 11 and crystallizes.

At this time, as shown in an enlarged manner in FIG. 9, the collision surface of the wire mesh 54 with which the reducing agent collides is a curved surface, and the spray of the reducing agent does not spread in a flat shape but forms a liquid film along the curved surface. After being spread out, it is sheared when leaving the wire mesh 54 and is easily made into fine particles. Moreover, when exhaust gas passes through the wire mesh 54, strong turbulence is generated and the flow velocity is increased, so that the spray of the reducing agent is easily affected by the flow of the exhaust gas, and the evaporation property is improved. Is becoming easier to promote.
The mixer main body 52 in the mixer unit 11 of the present embodiment has a configuration including five wire meshes 54, and atomization due to the above-described action is repeated. Therefore, the spray of the reducing agent passing through the mixer main body 52 is efficiently atomized and easily mixed and diffused in the exhaust gas.

Since the spray of the reducing agent that has passed through the mixer main body 52 is sufficiently atomized in this way, it can be easily diffused into the exhaust passage by passing through the diffusion member 53 on the downstream side. As a result, like spray of a reducing agent is uniformly flows relative to the inlet entire surface of the reduction catalyst, it can be carried out using the entire reducing catalyst reduction of the NO _X in the exhaust gas efficiently.

It is a figure showing composition of an exhaust-air-purification device concerning an embodiment of the invention. It is a figure for demonstrating the structure of the mixer unit with which the exhaust gas purification apparatus concerning embodiment of this invention was equipped. It is a disassembled perspective view which shows the structure of a mixer unit. It is a disassembled perspective view which shows the structure of the mesh plate which comprises a mixer unit. It is sectional drawing of the mixer main-body part which comprises a mixer unit. It is a figure which shows the state which the adjacent wire mesh contacted. It is a figure for demonstrating the arrangement configuration of a some mesh plate. It is a figure for demonstrating the structural example of a diffusion member. It is a figure for demonstrating the flow of the spray of the reducing agent which passes a mixer unit. It is a figure for demonstrating the structure of the conventional exhaust gas purification apparatus.

Explanation of symbols

5: internal combustion engine, 10: exhaust purification device, 11: mixer unit, 13: reduction catalyst, 17: downstream oxidation catalyst, 19: upstream oxidation catalyst, 25: exhaust pipe, 30: reducing agent supply device, 31: storage Tank: 33: Pump, 35: Injector, 37: Reducing agent supply path, 51: Mesh plate, 52: Mixer body, 53: Diffusion member, 54: Wire mesh, 55: Fixing plate, 55a: Opening, 55b : Groove part, 61: diffusion part (flat plate), 62: support part

Claims (4)

In an exhaust emission control device for an internal combustion engine, comprising: a reduction catalyst disposed in an exhaust passage of the internal combustion engine; and a reducing agent injection unit for injecting a reducing agent into the exhaust passage upstream of the reduction catalyst.
A mixer unit for mixing and diffusing the reducing agent and the exhaust gas is disposed upstream of the reducing catalyst and downstream of the injection position by the reducing agent injection unit,
The mixer unit includes: a mixer main body including a wire mesh arranged in a flow direction of exhaust gas; and a diffusion member disposed on a reduction catalyst side of the mixer main body. Exhaust purification equipment.   The mixer body portion is configured by fixing a plurality of mesh plates formed by holding the wire mesh on a fixing plate, and by fixing the fixing plates of the plurality of mesh plates, The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein a gap is formed between the wire meshes.   When the plurality of wire meshes constituting the mixer main body are viewed in the exhaust gas flow direction, at least one of the wire mesh openings is shifted from the position of the other wire mesh openings. The exhaust emission control device for an internal combustion engine according to claim 1 or 2. In a mixer unit for mixing and diffusing the reducing agent supplied to the exhaust passage and the exhaust gas, which is used in an exhaust purification device of an internal combustion engine that reduces and purifies NO _X in the exhaust gas using a reducing agent,
A mixer unit comprising: a mixer main body including a plurality of wire meshes arranged in a flow direction of exhaust gas; and a diffusion member arranged on the reduction catalyst side of the mixer main body.

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