JP2012067697A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device which can suppress a pressure loss and the lowering of an exhaust emission temperature while suppressing an increase in weight and cost.SOLUTION: The exhaust emission control device includes at least two sets of catalysts 22, 22 arranged in series in the axial direction of a cylindrical casing 21, a first inlet space 23 provided at one end in the cylindrical casing 21 and having an exhaust inlet port 26 and a first communication port 31, a second inlet space 24 formed at the other end in the cylindrical casing 21 and having a second communication port 32, an outlet space 25 formed between the two sets of catalysts 22, 22 in the cylindrical casing 21 and having an exhaust outlet port 27, a communication passage 30 connecting the first communication port 31 and the second communication port 32, and a partition board 33 provided in the outlet space 25 and dividing the inside of the cylindrical casing 21 into two in the axial direction.

Description

  The present invention relates to an exhaust gas purification device for an internal combustion engine, and more particularly to an exhaust gas purification device that removes nitrogen oxides in exhaust gas.

  An exhaust gas from an internal combustion engine (hereinafter also referred to as an engine), particularly a diesel engine, contains nitrogen oxides (hereinafter referred to as NOx) that are air pollutants. Accordingly, a selective catalytic reduction (hereinafter abbreviated as SCR) for purifying NOx is installed in the exhaust passage of the engine, and urea water as a reducing agent is added to the exhaust flowing into the SCR. Thus, a technique is known in which the exhaust gas is purified by reducing NOx in the exhaust gas in the SCR.

  The SCR is configured, for example, by supporting a catalyst on a honeycomb structure carrier in which a plurality of minute holes parallel to each other in the axial direction communicate with each other. In the exhaust gas purification apparatus using the SCR, a nozzle as a urea water addition apparatus for adding urea water to the exhaust gas is provided on the upstream side of the SCR. The urea water added from the nozzle is decomposed into ammonia by exhaust heat in the exhaust pipe and on the SCR, and acts as a reducing agent for NOx. Ammonia in the vicinity of the SCR is once adsorbed by the SCR, and NOx is reduced to nitrogen by promoting the denitration reaction between the ammonia and NOx in the exhaust gas by the SCR.

  By the way, from the viewpoint of mass productivity, the SCR is standardized, and in the SCR of this standard product, the amount of NOx reduced by one SCR is limited to some extent. For this reason, in the case of an engine with a large displacement such as a large truck (usually a diesel engine), a catalyst capacity may be secured by installing a plurality of SCRs. In this case, as shown in FIG. 3 (a), a plurality of [two in FIG. 3 (a)] SCRs 62 are arranged in series in one casing 61 (see FIG. 2 of Patent Document 1). ). At this time, the outer periphery of the SCR 62 is surrounded by the mat member 65 in order to allow a dimensional error of the outer periphery of the SCR 62 with respect to the inner periphery of the casing 61.

  As shown in FIG. 3 (b), a plurality of (two in FIG. 3 (b)) SCRs 72 are respectively housed in the casing 71, and the plurality of casings 71 are arranged in parallel so that The pipes 73a, 73a are connected to the inlet pipe 73 and assembled together, and the downstream ends of the exhaust outlet pipes 74a, 74a of each casing 71 are connected to the outlet pipe 74 and assembled (see Patent Document 1). (See FIG. 3).

  In addition, in parallel arrangement, as shown in FIG. 3 (c), a plurality of (two in FIG. 3 (c)) SCRs 82 are respectively housed in the casing 81, and the plurality of casings 81 are sealed. The upstream and downstream portions of the casing 81 are partitioned and held by the two support plates 87 and 87 which are arranged in parallel in the housing 86 and are provided with rectangular and circular holes 88. Some will do.

Japanese National Patent Publication No. 10-511038

  However, as shown in FIG. 3A, in the case where a plurality of SCRs 62 are arranged in series (series flow path method), the pressure loss increases according to the number of SCRs as compared with the case of a single SCR. There is. On the other hand, as shown in FIG. 3B, in the case where a plurality of SCRs 72 are arranged in parallel (parallel flow path system), the pressure loss is reduced according to the number of SCRs as compared with the case of a single SCR. However, since a plurality of SCRs 72 are respectively housed in the casing 71, a new problem arises in that the apparatus becomes larger and the weight increases, and the cost increases accordingly. Also, as shown in FIG. 3C, when a plurality of SCRs 82 are arranged in parallel within the housing 86, it is necessary to provide the support plate 87, so that the apparatus is also increased in size and weight, and the cost is increased. Will also increase.

  Further, in order to reduce NOx by SCR, it is necessary to keep the exhaust temperature at a high temperature. However, in the case of the parallel flow path system as shown in FIG. 3B, a plurality of SCRs 72 are housed in the casing 71, respectively. Therefore, there is a problem that the surface area of the entire apparatus is increased, and the heat insulation performance is lower than that of the serial flow path type as shown in FIG. In addition to the above, in the case of the parallel flow path system as shown in FIG. 3B, the number of end plates 71 a of the casing 71 to which the pipe 73 a into which the exhaust flows is connected increases according to the number of SCRs 72. Therefore, in the case of the parallel flow path system as shown in the figure, even if high temperature exhaust gas flows into the casing 71, the number of end plates 71a in contact with the outside air is large. However, there is a problem that heat dissipation is further promoted.

Further, regarding the mountability when the exhaust emission control device is disposed under the floor of a vehicle or the like, a device having a higher degree of freedom in placement and good in-vehicle properties is required.
Such a problem can occur not only in the SCR but also in an exhaust purification apparatus equipped with various exhaust purification catalysts in the casing.
The present invention has been devised in view of such problems, and it is an object of the present invention to provide an exhaust purification device capable of suppressing an increase in weight and cost and suppressing a pressure loss and a decrease in exhaust temperature. .

  In order to solve the above problems, an exhaust emission control device of the present invention is provided with at least two sets of catalysts arranged in series in the axial direction of a cylindrical casing, and one end in the cylindrical casing, A first inlet space having a first series of openings, a second inlet space provided at the other end in the cylindrical casing and having a second communication port, and the two sets of catalysts in the cylindrical casing. An outlet space provided between the first inlet port and the second inlet port, the outlet passage having an exhaust outlet, the communication port connecting the first inlet space and the second inlet space; And a partition plate that is provided in the outlet space and bisects the axial direction of the cylindrical casing.

Moreover, it is preferable that the said partition plate has a some through-hole.
Moreover, it is preferable that each of the two sets of catalysts is composed of a selective reduction catalyst provided on the exhaust upstream side and an oxidation catalyst provided on the exhaust downstream side.

  According to the exhaust gas purification apparatus of the present invention, the exhaust gas flowing from the exhaust inlet of the first inlet space is directed to the catalyst adjacent to the first inlet space, and the second inlet space passes through the communication path from the first series of openings. Into the exhaust gas toward the catalyst adjacent to the second inlet space. Therefore, since at least two sets of catalysts can be arranged in series in one cylindrical casing, it is possible to adopt a parallel flow path method, so that the pressure loss is higher than that of a single catalyst type or a single catalyst. Can be suppressed.

  Moreover, since a plurality of catalysts are arranged in series in one cylindrical casing while adopting the parallel flow path method, the surface area of the casing in contact with the outside air is reduced, and heat dissipation can be suppressed. Furthermore, since the catalyst is disposed in one cylindrical casing, the entire apparatus can be made compact, an increase in weight and cost can be suppressed, and mountability can be ensured.

As described above, improvement in engine performance, weight reduction, cost reduction, and improvement in the purification rate of NOx in exhaust gas can be achieved in a balanced manner.
Further, the flow rate of exhaust gas passing through at least two sets of catalysts can be adjusted by a partition plate provided in the outlet space. At this time, when a large number of through holes are formed in the partition plate, the flow rate adjustment based on the offset amount of the partition plate does not become sensitive. That is, since it is not necessary to arrange the partition plate with high accuracy, the manufacturing cost can be suppressed.

  In addition, the two sets of catalysts can be made more compact when the selective reduction catalyst provided on the exhaust upstream side and the oxidation catalyst provided on the exhaust downstream side are integrally molded. Good mountability.

1 is a schematic axial sectional view showing a configuration of an exhaust emission control device according to an embodiment of the present invention. It is a whole lineblock diagram explaining the exhaust-air-purification device concerning one embodiment of the present invention. FIGS. 3A and 3B are schematic cross-sectional views for explaining conventional problems. FIG. 3A is a series arrangement, FIG. 3B is a parallel arrangement, and FIG. Furthermore, they are arranged in parallel in the housing.

[1. Constitution]
[1-1. overall structure]
Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment.

An exhaust emission control device according to this embodiment will be described with reference to FIGS. 1 and 2. The present exhaust purification apparatus can be applied not only to a vehicle but also to a vehicle equipped with an engine, for example, a ship, etc., but here, an example applied to a vehicle such as a general passenger car, a truck, or a bus will be described. .
As shown in FIG. 2, the engine 40 is here configured as a diesel engine of an in-line 6-cylinder engine. Each cylinder of the engine 40 is provided with a fuel injection valve 41. Each fuel injection valve 41 is supplied with pressurized fuel from a common rail 42, and injects fuel into the cylinder of the corresponding cylinder when the valve is opened. The engine 40 may be a gasoline engine, and the number of cylinders is not limited to this.

  An intake manifold 43 is mounted on the intake side of the engine 40, and an air passage 45 connected to the intake manifold 43 is provided with an air cleaner 45, a compressor 46 a of a turbocharger 46 and an intercooler 47 from the upstream side. An exhaust manifold 48 is mounted on the exhaust side of the engine 40, and a turbine 46b of a turbocharger 46 connected coaxially with the compressor 46a is connected to the exhaust manifold 48. An exhaust passage 49 is connected to the turbine 46b. An exhaust purification device 1 is provided in the middle of the exhaust passage 49.

The exhaust purification device 1 includes an upstream side exhaust purification device 10 provided on the exhaust upstream side, and a downstream side exhaust purification device 20 provided on the exhaust downstream side of the upstream side exhaust purification device 10. The device 10 and the downstream side exhaust purification device 20 are connected by an intermediate pipe 19.
The upstream side exhaust purification apparatus 10 includes, in a cylindrical casing 11, a pre-stage oxidation catalyst 12 disposed on the upstream side, and a particulate filter (hereinafter abbreviated as DPF) 13 disposed on the downstream side. And are built in. Hereinafter, the upstream side exhaust purification device 10 is referred to as a DPF device 10.

  In the downstream side exhaust purification device 20, two sets of catalysts 22, 22 are arranged in series in the axial direction of the cylindrical casing 21 in a cylindrical cylindrical casing 21. This catalyst 22 is a so-called zone coat catalyst in which different catalyst substances are carried (coated) on one carrier, and the exhaust upstream side is a selective catalytic reduction (hereinafter abbreviated as SCR) 22a. The downstream side is configured as a post-stage oxidation catalyst 22b. Hereinafter, the downstream side exhaust purification device 20 is referred to as an SCR device 20.

  Further, a urea water addition nozzle 15 is provided on the exhaust downstream side of the DPF device 10 and on the upstream side of the intermediate pipe 19, and the urea water addition nozzle 15 is urea as a reducing agent pumped from a tank (not shown). Water is injected and added into the exhaust toward the SCR device 20. The amount of urea water added and the timing of addition are controlled by a controller (ECU, Engine (electronic) Control Unit) 50.

  The controller 50 includes a CPU that executes various arithmetic processes related to engine control, exhaust purification control, and the like, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores CPU calculation results, and the like. And an input / output port for inputting / outputting signals to / from.

[1-2. DPF device]
The DPF device 10 has a function of collecting particulate matter (hereinafter abbreviated as PM) contained in exhaust gas and a function of continuously oxidizing and removing the collected PM. In addition, PM is a particulate material in which fuel, lubricant components, sulfur compounds, and the like that remain unburned around carbon black smoke (soot) are attached.

The pre-stage oxidation catalyst 12 is an oxidation catalyst having an oxidation performance with respect to components in exhaust gas, and is a catalyst in which a catalyst material is supported on a honeycomb-shaped carrier made of metal, ceramics or the like. Components in the exhaust gas oxidized by the pre-stage oxidation catalyst 12 include NO, hydrocarbons in unburned fuel, and carbon monoxide. For example, when NO is oxidized by the pre-stage oxidation catalyst 12, NO ₂ is generated.

  The DPF 13 is a porous filter (for example, a ceramic filter) that collects PM. The inside of the DPF 13 is divided into a plurality of portions along the flow direction of the exhaust by a porous wall. A large number of pores having a size commensurate with the particulates of PM are formed in the wall. When the exhaust gas passes near or inside the wall body, PM is collected on the wall body and the wall body surface, and the exhaust gas is filtered. Such regeneration control of the DPF 13 is controlled by the controller 50.

  A space called a mixing chamber 14 is formed on the downstream side of the DPF 13. An intermediate pipe 19 is disposed in the mixing chamber 14 so as to penetrate the peripheral wall of the casing 11. The intermediate pipe 19 constitutes a part of the exhaust passage 49, and is the most general cylindrical pipe here. In the exhaust gas purification apparatus 1 according to the present embodiment, the upstream side 19a of the intermediate pipe 19 passes through the peripheral wall of the casing 11 and is cantilevered by the peripheral wall of the casing 11. The mixing chamber 14 and the intermediate pipe 19 communicate with each other with the side as an open end.

  The intermediate pipe 19 is not limited to a general cylindrical pipe, and may be another cylindrical pipe. In addition, the communication structure between the mixing chamber 14 and the intermediate pipe 19 is not limited to this, and for example, a hole (not shown) that connects the inside and outside of the intermediate pipe 19 to the exposed portion (insertion portion) of the intermediate pipe 19 into the mixing chamber 14. A plurality of abbreviations) may be provided, and the inside of the mixing chamber 14 and the inside of the intermediate pipe 19 may be communicated with each other through these holes.

[1-3. SCR device]
The SCR 22a is a urea addition type nitrogen oxide selective reduction type catalyst, which has a function of hydrolyzing urea water added from the upstream side to ammonia and adsorbing ammonia, and further using a reduction action by the adsorbed ammonia. NOx in exhaust gas is reduced to N ₂ . The type of catalyst supported on the SCR 22a is arbitrary, and for example, it is conceivable to use a zeolite type, a vanadium type, or the like. Further, a reducing agent other than urea water may be used.

The post-stage oxidation catalyst 22b is an oxidation catalyst for removing excess ammonia in the reduction reaction at the SCR 22a.
As shown in FIG. 1, in the cylindrical casing 21 of the SCR device 20, two sets of catalysts 22 including an SCR 22 a and a post-stage oxidation catalyst 22 b are arranged in series with an interval in the axial direction of the cylindrical casing 21. An exhaust outlet 27 is provided in the space between the two sets of catalysts 22 and 22. Hereinafter, the space between them is referred to as an exit space 25. The two sets of catalysts 22 and 22 are disposed so as to face each other with the exhaust outlet 27 interposed therebetween. An exhaust pipe 29 is connected to the exhaust outlet 27. The exhaust pipe 29 constitutes a part of the exhaust passage 49 and is the most general cylindrical pipe here, but is not limited to this, and may be another cylindrical pipe.

  Spaces are provided at both ends of the cylindrical casing 21 by disposing the catalyst 22 separately from the inner surface of the axial end portion of the cylindrical casing 21. Among these, in one space provided at one end of the cylindrical casing 21, an exhaust inlet 26 is provided in the peripheral wall of the cylindrical casing 21. An intermediate pipe 19 that communicates with the DPF device 10 is connected to the exhaust inlet 26. Hereinafter, this space provided with the exhaust inlet 26 is referred to as a first inlet space 23.

Of the two sets of catalysts 22, 22, the catalyst 22 on the first inlet space 23 side is provided with the SCR 22 a on the side adjacent to the first inlet space 23, and the post-stage oxidation catalyst 22 b on the side adjacent to the outlet space 25. Configured.
The first inlet space 23 is further provided with a first series of openings 31 on the peripheral wall of the cylindrical casing 21. In the present embodiment, as shown in FIG. 1, the first series passage 31 is provided at a position substantially opposite to the exhaust inlet 26. By providing the first series of openings 31 in this manner, the flow resistance can be suppressed, and the exhaust gas flowing into the cylindrical casing 21 from the exhaust inlet 26 is smoothly directed toward the SCR 22a and the first series of openings 31. Can flow into.

In addition, when considering the mountability to a vehicle or the like, the arrangement relationship with surrounding devices, and the like, for example, a configuration in which the exhaust inlet 26 is provided in the end wall of the cylindrical casing 21 and the first series of openings 31 is provided in the peripheral wall. Is also possible. Conversely, a configuration in which the exhaust inlet 26 is provided on the peripheral wall of the cylindrical casing 21 and the first series passage 31 is provided on the end wall is also possible.
A second communication port 32 is provided in the peripheral wall of the cylindrical casing 21 in the other space provided at the other end of the cylindrical casing 21. Hereinafter, this space is referred to as a second entrance space 24. Of the two sets of catalysts 22, 22, the catalyst 22 on the second inlet space 24 side is provided with the SCR 22 a on the side adjacent to the second inlet space 24, and the post-stage oxidation catalyst 22 b on the side adjacent to the outlet space 25. Configured.

  Both ends of a communication pipe (communication path) 30 are connected to a first communication port 31 provided in the first inlet space 23 and a second communication port 32 provided in the second inlet space 24, respectively. The space 23 and the second inlet space 24 are communicated with each other by the communication pipe 30 through the first series port 31 and the second communication port 32. The communication pipe 30 is the most common cylindrical pipe here, and extends in the axial direction of the cylindrical casing 21. The communication pipe 30 is not limited to a general cylindrical pipe, and may be another cylindrical pipe.

  A partition plate 33 that divides the inside of the cylindrical casing 21 into two in the axial direction is disposed in the outlet space 25. The partition plate 33 is a plate that is provided at a position where the exhaust outlet 27 provided in the outlet space 25 is divided into two, and partitions the inside of the cylindrical casing 21 into two spaces with the exhaust outlet 27 interposed therebetween. That is, due to the partition plate 33, the inside of the cylindrical casing 21 is formed between the space of the catalyst 22 disposed adjacent to the first inlet space 23 and the catalyst 22 disposed adjacent to the second inlet space 24. Divided into space.

  The partition plate 33 is formed in substantially the same shape as the cross section orthogonal to the axial direction of the cylindrical casing 21, and is fixed to the inner peripheral wall of the cylindrical casing 21. In the present embodiment, the partition plate 33 is provided at the axial center of the cylindrical casing 21. The partition plate 33 is provided with a plurality of small through holes 33h. The plurality of through holes 33h may be provided, for example, in a substantially uniform manner, or may be provided densely in a specific portion, and the arrangement and number thereof are not limited.

Further, the outer periphery of the two sets of catalysts 22 and 22 is surrounded by mat members 28 and 28, respectively, and a dimensional error of the outer periphery of the catalyst 22 with respect to the inner periphery of the cylindrical casing 21 is allowed. In the present embodiment, the two sets of catalysts 22 and 22 are formed in a circular cross section, but the shape of the catalyst is not limited to this.
Note that the SCR device 20 according to this embodiment is formed symmetrically about the outlet space 25 except for the exhaust inlet 26. That is, the cylindrical outlet space 25 is formed symmetrically about the plane perpendicular to the axial direction at the center in the axial direction.

[2. Action]
Since the exhaust gas purification apparatus 1 according to the present embodiment is configured as described above, the exhaust gas is purified as follows.
During operation of the engine 40, the exhaust discharged from the engine 40 is introduced into the DPF device 10 through the upstream portion of the exhaust passage 49, transferred to the mixing chamber 14 after passing through the pre-stage oxidation catalyst 12 and the DPF 13, It is introduced into the intermediate pipe 19. Then, the gas flows through the intermediate pipe 19 and is introduced into the SCR device 20 from the exhaust inlet 26. After passing through the SCR 22a and the post-stage oxidation catalyst 22b, the exhaust pipe 27 passes through the exhaust pipe 29 and is discharged into the atmosphere. At this time, PM in the exhaust is collected in the DPF 13, and NOx in the exhaust is reduced in the SCR 22a, and these actions prevent the discharge of harmful components into the atmosphere.

  More specifically, after PM in exhaust gas is collected by the DPF 13, urea water as a reducing agent is exhausted from the urea water addition nozzle 15 provided on the upstream side of the intermediate pipe 19 toward the SCR device 20. To be added. The added urea water is hydrolyzed by exhaust heat while being mixed with exhaust gas in the intermediate pipe 19 to generate ammonia, and is introduced into the SCR device 20 from the exhaust inlet 26.

  Exhaust gas containing ammonia introduced from the exhaust inlet 26 first flows into the first inlet space 23, exhausts toward the SCR 22 a adjacent to the first inlet space 23, and passes through the communication pipe 30 from the first series outlet 31. It is divided into exhaust toward the second inlet space 24. Exhaust gas that has directly flowed into the SCR 22a from the first inlet space 23 flows through the SCR 22a and the post-stage oxidation catalyst 22b, passes through the outlet space 25, and then is discharged from the exhaust outlet 27 through the exhaust pipe 29 into the atmosphere.

On the other hand, the exhaust gas that has flowed from the first inlet space 23 through the communication pipe 30 into the second inlet space 24 flows into the SCR 22a adjacent to the second inlet space 24, flows through the SCR 22a and the post-stage oxidation catalyst 22b, and exits the space 25. After passing through, the exhaust outlet 27 passes through the exhaust pipe 29 and is discharged into the atmosphere.
At this time, ammonia contained in the exhaust is adsorbed by the two sets of SCRs 22a and 22a, and NOx in the exhaust is reduced to purify the exhaust. Further, surplus ammonia that has not been adsorbed by the SCRs 22a and 22a is removed by the two sets of post-stage oxidation catalysts 22b and 22b, thereby preventing ammonia from being discharged into the atmosphere.

[3. effect]
Therefore, according to the exhaust purification apparatus according to the present embodiment, the two sets of catalysts 22 and 22 can be arranged in series in one cylindrical casing 21, but the parallel flow path system can be used. Pressure loss can be suppressed as compared with the flow path system and the catalyst alone. Moreover, since the two sets of catalysts 22 and 22 are arranged in series in the cylindrical casing 21 while adopting the parallel flow path method, the surface area of the cylindrical casing 21 in contact with the outside air is reduced, and heat dissipation is suppressed. be able to. Further, the entire SCR device 20 can be made compact, an increase in weight and cost can be suppressed, and mountability can be ensured.

Further, the two sets of catalysts 22 and 22 are configured as zone coat catalysts in which different catalyst substances are supported (coated) on one carrier so that the upstream side of the exhaust gas becomes the SCR 22a and the downstream side of the exhaust gas oxidation catalyst 22b. Therefore, the overall configuration of the exhaust emission control device 1 can be made more compact, and the mountability is further improved.
Further, since the partition plate 33 provided in the outlet space 25 can define the size of the outlet space 25 that is a space through which the exhaust flows and the area of the exhaust outlet 27, the catalyst 22 adjacent to the first inlet space 23 can be defined. It is possible to adjust the flow rate of the exhaust toward the exhaust and the exhaust toward the second inlet space 24 from the first series opening 31 through the communication pipe 30. In the present embodiment, as shown in FIG. 1, the partition plate 33 is installed at the center of the cylindrical casing 21 in the axial direction, but the flow resistance when passing through the two sets of catalysts 22 and 22 is larger. The exhaust space 25 of the catalyst may be deviated from the axial center of the cylindrical casing 21 so that the catalyst outlet space 25 is widened, and the exhaust gas may be distributed evenly to both catalysts.

If the area of the outlet space 25 and the area of the passage that goes directly to the exhaust outlet 27 are increased, the exhaust gas can be easily circulated. Therefore, the exhaust gas flow rate can be increased, and conversely, if these are reduced, the exhaust gas is difficult to circulate. The exhaust flow rate can be reduced. Further, since the partition plate 33 is provided with a plurality of small through holes 33h, the exhaust can pass through the outlet space 25 slightly through the plurality of through holes 33h. . Therefore, the amount of deviation of the partition plate 33, that is, the adjustment of the exhaust flow rate according to the installation position of the partition plate 33 does not become too sensitive, and the partition plate 33 does not need to be installed in the cylindrical casing 21 with high accuracy, thereby reducing the manufacturing cost. can do.
As described above, improvement in engine performance, weight reduction, cost reduction, and improvement in the purification rate of NOx in exhaust gas can be achieved in a balanced manner.

[4. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

In the above embodiment, the DPF device 10 and the SCR device 20 are arranged adjacent to each other with the axial directions of the casings aligned, but the arrangement of the DPF device 10 and the SCR device 20 is not limited to this, for example, DPF The device 10 and the SCR device 20 may be arranged so that their axial directions intersect with each other and connected by a curved intermediate pipe.
Further, the SCR device 20 according to the above-described embodiment is formed symmetrically with respect to a plane orthogonal to the axial direction at the central portion in the axial direction of the cylindrical outlet space 25 except for the exhaust inlet 26. However, the arrangement of the two sets of catalysts 22 and 22 and the positions of the first communication port 31 and the second communication port 32 do not necessarily have to be symmetrical.

Further, the number of catalysts is not limited to two sets, and two or more sets of catalysts may be arranged in the cylindrical casing 21. Further, the catalyst is not limited to the zone coat catalyst, and the post-stage oxidation catalyst may be provided as a separate body not on the cylindrical casing 21 but on the downstream side of the SCR device 20.
Further, since the paths of the exhaust gas flowing through the two sets of catalysts are uneven, the installation position of the partition plate 33 is the axial center of the cylindrical casing 21 or a position that equally divides the area of the exhaust outlet 27. It is not possible to flow exhaust gas equally between the two sets of catalysts. Therefore, in order to flow the exhaust gas equally to the two sets of catalysts, it is necessary to deliberately shift the installation position of the partition plate 33 from the axial center of the cylindrical casing 21 and the position where the area of the exhaust outlet 27 is equally divided. .

  Moreover, the through-hole of a partition plate is not essential, and the through-hole may not be formed. Further, the catalyst is not limited to the SCR or the post-stage oxidation catalyst, and if the exhaust gas purification catalyst is equipped with at least two sets of casings in the casing, the parallel flow path system is configured while being arranged in series in the axial direction of the casing. Can do.

1 Exhaust purification device 10 DPF device (upstream exhaust purification device)
12 Pre-stage oxidation catalyst 13 DPF (particulate filter)
15 Urea water addition nozzle 19 Intermediate pipe 20 SCR device (downstream exhaust purification device)
21 Cylindrical casing 22 Catalyst 22a SCR (selective reduction catalyst)
22b Rear-stage oxidation catalyst 23 First inlet space 24 Second inlet space 25 Outlet space 26 Exhaust inlet 27 Exhaust outlet 29 Exhaust pipe 30 Communication pipe (communication path)
31 First communication port 32 Second communication port 33 Partition plate 33h Through hole 40 Engine 49 Exhaust passage 50 Controller

Claims (3)

At least two sets of catalysts arranged in series in the axial direction of the cylindrical casing;
A first inlet space provided at one end in the cylindrical casing and having an exhaust inlet and a first series of outlets;
A second inlet space provided at the other end in the cylindrical casing and having a second communication port;
An outlet space provided between the two sets of catalysts in the cylindrical casing and having an exhaust outlet;
A communication path that connects the first communication port and the second communication port and communicates the first inlet space and the second inlet space;
An exhaust emission control device comprising: a partition plate provided in the outlet space and dividing the inside of the cylindrical casing into two in the axial direction. The exhaust emission control device according to claim 1, wherein the partition plate has a plurality of through holes. 3. The two sets of catalysts are each composed of a selective reduction catalyst provided on the exhaust upstream side and an oxidation catalyst provided on the exhaust downstream side. Exhaust purification equipment.

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