JP2011231672A - Exhaust gas purifying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas purifying apparatus capable of suppressing heat dissipation of a second purifier in a housing and maintaining the second purifier more stably than before in the housing, even with a configuration having a path of exhaust gas in which the flow is reversed, in the housing.SOLUTION: A plurality of first purifiers are in contact with an outer circumferential surface of the second purifier and disposed with intervals left between the first purifiers. The second purifier is held with an interval left with an inner wall of the housing 11 via the plurality of first purifiers and is formed with a communication passage 24. The first purifiers are equipped with a first exhaust inlet port connected to an inlet port of the housing 11 and a first exhaust outlet port positioned on an opposite side to the first exhaust inlet port and communicated with the communication passage 24. The second purifier includes a second exhaust inlet port communicated with the communication passage 24 and a second exhaust outlet port connected to the outlet port of the housing 11, and is mounted with an additive agent injection valve for injecting an additive agent to exhaust gas discharged from a first exhaust outlet port side of the communication passage.

Description

  The present invention relates to an exhaust gas purification device, and more particularly to an exhaust gas purification device including an oxidation catalyst and an SCR catalyst.

As a conventional exhaust gas purification device, for example, there is a particle filter mechanism disclosed in Patent Document 1.
The particle filter mechanism disclosed in Patent Document 1 is connected, for example, between an automobile engine and an exhaust port.
In this particle filter mechanism, an outer wall, an inner wall, and a common annular wall are provided in the housing, and a first path section, a second path section, and a third path section are formed in the housing by these walls. .
A catalytic converter and a particle filter are installed in the first path section.
The catalytic converter removes sulfur oxide (SOx) and nitrogen oxide (NOx) contained in the exhaust gas entering from the inlet of the housing, and the particle filter removes soot particles (CO) contained in the exhaust gas.
The second path section is formed to be located on the outer peripheral side of the first path section, and no catalytic converter or particle filter is installed in the second path section.
The third path section is formed so as to be located in the center of the housing, that is, on the inner circumference side of the first path section, and a particle filter is installed in the third path section.

The exhaust gas from the engine is led to the exhaust port through the particle filter mechanism. For example, in the embodiment shown in FIG. 2a of Patent Document 1, the exhaust gas in the particle filter mechanism has a first path section and a second path section. Pass through in the order of the third route section.
In the first path section, the exhaust gas flows from the inlet side to the outlet side of the housing, in the second path section, the exhaust gas flow is reversed and flows from the outlet side to the inlet side, and in the third path section. Then, the flow is reversed again and flows from the inlet side to the outlet side.
According to the particle filter mechanism disclosed in Patent Document 1, the length of the particle filter mechanism is shortened by making the flow of exhaust gas reverse through the first path section, the second path section, and the third path section. be able to.

As another conventional technique, for example, an exhaust gas aftertreatment system for a diesel engine disclosed in Patent Document 2 is known.
The exhaust gas aftertreatment system disclosed in Patent Document 2 includes an exhaust gas particulate filter, a nitrogen oxide reduction catalyst connected to the downstream side of the exhaust gas particulate filter, and a reducing agent supply device.
According to this exhaust gas aftertreatment system, the exhaust gas particulate filter has a filter inner area for the filtered exhaust gas, with the exhaust gas flowing substantially radially into the filter body, It is embodied in the form of a porous cylindrical filter body that flows the exhaust gas axially out of the zone.
The reducing agent is supplied into the filter inner area by a reducing agent supply device.

Special table 2009-520906 JP-T-2006-504026

However, the particle filter mechanism disclosed in Patent Document 1 realizes a long exhaust path by forming the first path section, the second path section, and the third path section, while reducing the length of the particle filter mechanism. Only the advantages of are disclosed.
Further, in the exhaust gas aftertreatment system disclosed in Patent Document 2, an aqueous urea solution as a reducing agent is injected into the housing, but the SCR catalytic converter monolith is separated from the catalytic converter disk by a partition plate. The heat exchange between the two is not performed.
In the exhaust gas aftertreatment system disclosed in Patent Document 2, since the SCR catalytic converter / monolith is installed around the collection manifold at the center of the housing, the SCR catalytic converter / monolith is affected by external temperature changes. There is a problem that the temperature of the exhaust gas passing therethrough tends to decrease due to heat dissipation.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to dissipate heat from the second purifier in the housing, even if the exhaust gas path is reversed in the housing. The present invention provides an exhaust gas purification device that can hold the second purification body in the housing more stably than in the past.

  In order to solve the above problems, the present invention provides a plurality of first purifying bodies that purify exhaust gas discharged from an internal combustion engine, and a first purifying exhaust gas that has passed through the plurality of first purifying bodies. 2. An exhaust gas purification apparatus comprising: 2 purification bodies; and a housing in which the plurality of first purification bodies and the second purification bodies are housed, wherein the plurality of first purification bodies are outer peripheries of the second purification bodies. The second purifying body is in contact with a surface and spaced from the first purifying body, and the second purifying body is held at a distance from an inner wall of the housing via the plurality of first purifying bodies, and the housing A first exhaust that is connected to an inlet of the housing. A communication path is formed by the inner wall of the first purification body and an outer peripheral surface of the first purification body and an outer peripheral surface of the second purification body. Located on the opposite side of the inlet and the first exhaust inlet. A first exhaust outlet that communicates with the communication path, and the second purifier includes a second exhaust inlet that communicates with the communication path, and a second exhaust outlet that is connected to the outlet of the housing, 1. An additive injection valve for injecting additive to exhaust gas emitted from an exhaust outlet is provided.

According to the present invention, since the exhaust gas passing through the communication path with the first purification body surrounds the second purification body, the second purification body is hardly affected by the outside air and suppresses heat radiation of the second purification body. can do.
In addition, since the second purification body is held in the housing via the plurality of first purification bodies, the second purification body can be stably held on the center side in the housing.

  According to the present invention, in the above exhaust gas purification device, the first space portion is provided between the first exhaust outlet and the communication passage, and the second space is provided between the second exhaust inlet and the communication passage. There may be a space, and the flow of the exhaust gas may be reversed in the opposite direction in the first space and the second space.

  In this case, since the flow of the exhaust gas is reversed in the opposite direction in the first space portion and the second space portion, an exhaust gas path sufficiently longer than the length of the housing can be set.

  In the present invention, in the above exhaust gas purification device, the second purification body may be held by pressing the second purification body by a plurality of the first purification bodies.

  In this case, since the second purification body is held by the pressing of the first purification body, heat transfer between the first purification body and the second purification body is easy, and the heat of the first purification body is the first. By moving to the second purifier, the heat dissipation of the second purifier can be further suppressed.

  According to the present invention, in the above exhaust gas purification device, the first purification body may include a cover member that covers the periphery thereof, and the second purification body may be pressed by contact with the cover member. .

In this case, since only the cover member that covers the first purification body is interposed between the first purification body and the second purification body, heat transfer between the first purification body and the second purification body is easy. It becomes.
Further, the second purification body can be stably installed in the housing by the contact between the cover member and the second purification body.
Furthermore, it is not necessary to provide a cover member on the second purification body, and the manufacturing cost can be reduced as compared with the case where the cover member is provided on the second purification body.

  In the present invention, in the above exhaust gas purification device, the second purification body may be held by bonding with a plurality of the first purification bodies.

  In this case, since the first purification body and the second purification body are bonded, the second purification body can be held more stably in the housing as compared with the case where the first purification body is pressed against the second purification body. Can do.

  According to the present invention, in the above exhaust gas purification device, the first purification body includes a first cover member that covers the periphery thereof, and the second purification body includes a second cover member that covers the periphery thereof; The second purifier may be held by adhesion between the first cover member and the second cover member.

  In this case, a material suitable for bonding can be selected as the material of the first cover member and the second cover member. By selecting a material suitable for bonding, the second purifier is more stably placed in the housing. Can be retained.

  In the exhaust gas purification apparatus according to the present invention, the first purification body is an oxidation catalyst, the second purification body is an SCR catalyst, or an SCR catalyst and a DPF, and the additive is for an SCR catalyst. It may be a reducing agent.

In this case, a reducing agent necessary for the SCR catalyst can be added to the exhaust gas purified by the oxidation catalyst. Examples of the reducing agent include urea water and gaseous ammonia.
The added reducing agent is dispersed in the exhaust gas while passing through the communication path, and can be brought into a state suitable for the reducing action in the SCR catalyst.

  In the exhaust gas purification apparatus according to the present invention, the first purification body is an oxidation catalyst, the second purification body is a DPF, or a DPF and an SCR catalyst, and the additive is a regeneration of the DPF. Fuel may be used.

In this case, fuel necessary for DPF regeneration can be added to the exhaust gas purified by the oxidation catalyst.
The added fuel is heated and dispersed in the exhaust gas while passing through the communication path, burned in the DPF, and can be regenerated.

  According to the present invention, even in a configuration having an exhaust gas path in which the flow is reversed in the housing, in addition to suppressing heat dissipation of the second purification body in the housing, the second purification body is more stable than in the past. Thus, an exhaust gas purification device that can be held in the housing can be provided.

1 is an overall configuration diagram of an exhaust gas purification device according to a first embodiment of the present invention. It is an AA arrow line view of FIG. It is explanatory drawing which shows the flow of the exhaust gas in an exhaust-gas purification apparatus. It is a whole block diagram of the exhaust-gas purification apparatus which concerns on 2nd Embodiment. It is a BB line arrow directional view of FIG. It is principal part sectional drawing of the exhaust-gas purification apparatus which concerns on 3rd Embodiment. It is principal part sectional drawing of the exhaust-gas purification apparatus which concerns on 4th Embodiment. It is a whole block diagram of the exhaust-gas purification apparatus which concerns on 5th Embodiment.

(First embodiment)
Hereinafter, an exhaust gas purifying apparatus according to a first embodiment will be described with reference to the drawings.
1st Embodiment demonstrates the example applied to the vehicle carrying the diesel engine as an internal combustion engine.
An exhaust gas purification device 10 shown in FIG. 1 is installed in an exhaust passage through which exhaust gas discharged from a diesel engine (hereinafter referred to as “engine”) flows.

A housing 11 of the exhaust gas purifying apparatus 10 shown in FIG. 1 is a cylinder that connects one disc-shaped end wall portion 11A, the other disc-shaped end wall portion 11B, and the outer peripheral edges of the end wall portions 11A and 11B. 11C of surrounding wall parts are provided.
Four inlet holes 12 that serve as exhaust gas inlets are formed in the end wall portion 11A so that the center of the inlet hole 12 is disposed on a circle concentric with the disk-shaped disk of the end wall portion 11A. An outlet hole 13 serving as an outlet for exhaust gas is formed in the center of the wall portion 11B.
As shown in FIG. 1, between the engine and the exhaust gas purification device 10 in the exhaust passage, an upstream exhaust pipe 14 and an outlet end of the upstream exhaust pipe 14 are connected and branched into four branches 15A. A branch pipe 15 having the following structure is provided.
A downstream exhaust pipe 16 is provided between the exhaust gas purification device 10 and the outside of the vehicle in the exhaust passage.

  In the housing 11 shown in FIG. 2, four oxidation catalysts 17 disposed on the peripheral wall portion 11 </ b> C side and a DPF (diesel particulates) that removes particulate components in the exhaust gas held on the center side of the housing 11. A filter) 21 and an SCR (Selective Catalytic reduction) catalyst 22 are accommodated.

The oxidation catalyst 17 has a circular cross-sectional shape, and has a catalyst carrier such as honeycomb cordierite formed by extrusion molding, and an oxidation catalyst component supported on the surface of the catalyst carrier.
The oxidation catalyst 17 has a purification function of oxidizing carbon monoxide contained in the exhaust gas into carbon dioxide.
The oxidation catalyst 17 is fixed in a first canning case 18 as a first cover member.
In this embodiment, the oxidation catalyst 17 and the first canning case 18 constitute a first purifier.
In this embodiment, one end of the first canning case 18 is an inlet end 18A as a first exhaust inlet, and the inlet end 18A protrudes from the inlet hole 12 of the housing 11 to the end of the branch pipe 15. It is connected.
The other end of the first canning case 18 is an outlet end 18B as a first exhaust outlet, and the outlet end 18B located on the opposite side of the inlet end 18A is opposed to the other end wall portion 11B of the housing 11. .

As shown in FIG. 2, the respective oxidation catalysts 17 are installed at intervals in the circumferential direction from the oxidation catalysts 17 adjacent to each other in the circumferential direction of the peripheral wall portion 11 </ b> C.
The first canning case 18 of the oxidation catalyst 17 is fixed to the inner surface of the peripheral wall portion 11C of the housing 11 by welding.
The first canning case 18 constitutes a first exhaust gas path in which an exhaust gas flows from the inlet end 18A through the oxidation catalyst 17 toward the outlet end 18B.

The SCR catalyst 22 is a selective catalytic reduction type catalyst, and includes a catalyst component formed of a zeolitic material and a catalyst carrier that supports the catalyst component.
The SCR catalyst 22 has a purification function for purifying NOx contained in the exhaust gas.
The DPF 21 includes a honeycomb filter formed by extrusion, and the DPF 21 collects PM (Particulate Matter) in the exhaust gas.
In this embodiment, the DPF 21 and the SCR catalyst 22 are integrated by a second canning case 23 as a second cover member so that the SCR catalyst 22 is located on the downstream side of the DPF 21.
Here, the DPF 21 and the SCR catalyst 22 integrated by the second canning case 23 are referred to as an SCR / DPF composite 20.
In this embodiment, the SCR / DPF composite 20 and the second canning case 23 constitute a second purifier.

The SCR / DPF composite 20 is located on the center side of the housing 11, one end of the second canning case 23 is an inlet end 23 </ b> A as a second exhaust inlet, and the inlet end 23 </ b> A is one end wall of the housing 11. It faces the part 11A.
The other end of the second canning case 23 is an outlet end 23B as a second exhaust outlet, and the outlet end 23B protrudes outside from the outlet hole 13 of the housing 11 and is connected to the downstream exhaust pipe 16. .
The second canning case 23 is in contact with the first canning case 18 of each surrounding oxidation catalyst 17, and the SCR / DPF composite 20 is separated from the inner wall of the housing 11 by the respective oxidation catalysts 17 arranged around the housing. 11 is held on the center side.
That is, the SCR / DPF composite 20 in the second canning case 23 is held by the pressing of the first canning case 18.
The second canning case 23 constitutes a second exhaust gas path that serves as an exhaust gas flow from the inlet end 23A through the SCR / DPF composite 20 toward the outlet end 23B.

As shown in FIG. 2, first canning cases 18 having oxidation catalysts 17 adjacent to each other in the circumferential direction of the SCR / DPF composite 20 are disposed with a circumferential interval therebetween.
For this reason, a space defined by the second canning case 23 including the peripheral wall portion 11 </ b> C, the first canning case 18, and the SCR / DPF composite 20 is formed between the first canning cases 18.
This space constitutes a communication path 24 through which the exhaust gas that has passed through the oxidation catalyst 17 passes to the inlet end 23 </ b> A of the SCR / DPF composite 20.

Further, by providing a gap between the outlet end 18B of the first canning case 18 and the other end wall portion 11B of the housing 11, the outlet of the oxidation catalyst 17 in the housing 11 and the end wall portion 11B are provided. The first space 25 is formed.
The first space portion 25 is an annular space portion defined by the peripheral wall portion 11 </ b> C, the outlet end 18 </ b> B of the first canning case 18, and the second canning case 23.
For this reason, the oxidation catalyst 17 communicates with the inside of the housing 11 through the outlet end 18B.

Near the end wall 11B of the peripheral wall 11C of the housing 11 on the first exhaust outlet side of the communication passage 24, a urea water nozzle 27 as an additive injection valve is installed with the nozzle end facing the first space 25. Has been.
In this embodiment, the urea water nozzle 27 corresponds to the number of oxidation catalysts 17 and is installed in the vicinity of the outlet end 18 </ b> B of the first canning case 18.
The urea water nozzle 27 is connected via a pipe to a pump 28 that pumps the urea water for the SCR catalyst as an additive from the urea water tank 29 to the urea water nozzle 27.
The first space part 25 functions as a space part for reversing the flow of the exhaust gas that has passed through the oxidation catalyst 17 and for mixing the urea water injected into the exhaust gas that has passed through the oxidation catalyst 17 by the urea water nozzle 27. To do.

On the other hand, a space is provided between the inlet end 23A of the second canning case 23 and the one end wall 11A of the housing 11, so that the second cannula 23A is inserted between the end wall 11A and the inlet of the SCR / DPF composite 20. Two space portions 26 are formed.
The second space portion 26 is a space portion defined by the peripheral wall portion 11 </ b> C, the first canning case 18, and the inlet end 23 </ b> A of the second canning case 23.
For this reason, the SCR / DPF composite 20 communicates with the inside of the housing 11 through the inlet end 23A.

The first space portion 25 communicates with the communication passage 24 and functions to guide the exhaust gas to the communication passage 24 by reversing the flow direction of the exhaust gas that has passed through the oxidation catalyst 17.
The second space portion 26 communicates with the communication passage 24 and functions to guide the exhaust gas to the SCR / DPF composite 20 by reversing the direction of the flow of the exhaust gas that has passed through the communication passage 24.
The communication path 24 constitutes an inverted exhaust gas path that serves as an exhaust gas flow from the first space portion 25 communicating with the outlet end 18B toward the second space portion 26 communicating with the inlet end 23A.

In the exhaust gas purification apparatus 10 according to the first embodiment, the first exhaust gas path of the first canning case 18, the first space portion 25, the reverse exhaust gas path by the communication path 24, and the second in the housing 11. An exhaust gas flow path is formed by the space portion 26 and the second exhaust gas path of the second canning case 23.
The flow directions of the exhaust gas in the first exhaust gas path and the second exhaust gas path coincide with each other, and the flow direction of the reverse exhaust gas path is opposite to the flow direction of the exhaust gas in the first exhaust gas path and the second exhaust gas path. Direction.
That is, the exhaust gas flow path in the housing 11 is folded back in the housing 11, and a distance sufficiently longer than the length of the housing 11 is set.

Next, exhaust gas purification by the exhaust gas purification apparatus 10 according to the first embodiment will be described with reference to FIG.
In FIG. 3, the flow of exhaust gas in the exhaust gas purification device 10 is indicated by arrows.
The exhaust gas discharged from the engine passes through the upstream exhaust pipe 14 in the exhaust passage, is branched by the branch pipe 15 and passes through the oxidation catalyst 17.
In the oxidation catalyst 17, carbon monoxide contained in the exhaust gas is oxidized by the oxidation catalyst 17 into carbon dioxide.
The exhaust gas that has passed through the oxidation catalyst 17 exits from the outlet end 18 </ b> B of the first canning case 18 and reaches the first space 25.

In the first space portion 25, urea water is injected from the urea water nozzle 27, urea water is added to the exhaust gas, and is mixed with the exhaust gas.
The urea water is added according to the amount of NOx contained in the exhaust gas.
In the first space portion 25, the flow direction of the exhaust gas is reversed with the addition of urea water to the exhaust gas, and the exhaust gas passes through the communication path 24 from the first space portion 25 toward the second space portion 26. .
In the process where the exhaust gas passes from the first space 25 through the communication path 24 to the second space 26, the urea water added to the exhaust gas is hydrolyzed by the heat of the exhaust gas to become ammonia and carbon dioxide.
Due to the exhaust gas passing through the first canning case 18 and the exhaust gas passing through the communication passage 24, the second canning case 23 and the SCR / DPF composite 20 are heated from the surroundings and heated up.

The exhaust gas that has reached the second space portion 26 through the communication path 24 has its flow direction reversed in the second space portion 26, and the exhaust gas whose flow direction has been reversed enters the inlet end 23 </ b> A of the second canning case 23.
Exhaust gas passing through the second canning case 23 passes through the DPF 21. In the DPF 21, PM contained in the passing exhaust gas is collected, and the exhaust gas from which the PM has been removed passes through the SCR catalyst 22. When the PM collected by the DPF 21 is deposited, the PM is burned by fuel addition or the like to regenerate the DPF 21.

When the temperature of the exhaust gas passing through the SCR catalyst 22 is low, ammonia in the exhaust gas is adsorbed by the SCR catalyst 22 when the exhaust gas passes through the SCR catalyst 22.
When the exhaust gas temperature is high and the SCR catalyst 22 is equal to or higher than the catalyst activation temperature, the ammonia adsorbed on the SCR catalyst 22 reacts with NOx to become nitrogen and water, and the NOx in the exhaust gas is purified.
The exhaust gas that has passed through the SCR catalyst 22 is discharged from the outlet end 23B of the second canning case 23 to the downstream exhaust pipe 16.

The exhaust gas purifying apparatus 10 has the following effects.
(1) In the exhaust gas purification device 10, the first canning case 18 including the oxidation catalyst 17 and the communication path 24 surround the SCR / DPF composite 20. The exhaust gas passing through the case 18 and the communication passage 24 is covered. Since the exhaust gas that passes through the first canning case 18 and the communication passage 24 functions as a heat insulating layer for the outside air, the SCR / DPF composite 20 is not easily affected by the outside air and suppresses heat dissipation of the SCR / DPF composite 20. be able to.
(2) Since the second canning case 23 provided with the SCR / DPF composite 20 is held on the center side in the housing 11 via the first canning case 18, the second canning case 23 is used for holding the second canning case 23. There is no need for members. The DPF 21 and the SCR catalyst 22 can be stably installed in the housing 11.

(3) Since the SCR / DPF composite 20 is held by pressing the first canning case 18, heat transfer between the oxidation catalyst 17 and the SCR / DPF composite 20 is easy. That is, the heat of the oxidation catalyst 17 on the upstream side of the SCR / DPF composite 20 in the exhaust gas path can be transferred to the SCR / DPF composite 20, and the heat dissipation of the SCR / DPF composite 20 is further suppressed. Can do.
(4) Even if the SCR / DPF composite 20 is thermally expanded in the direction of expanding the diameter by the heat of the exhaust gas, the first canning case 18 presses the second canning case 23 of the SCR / DPF composite 20, The thermal expansion of the SCR / DPF composite 20 can be suppressed.
(5) A first exhaust gas path that passes through the plurality of oxidation catalysts 17 is set on the upstream side of the exhaust gas path in the housing 11, and a second exhaust gas path that passes through a single SCR / DPF composite 20 on the downstream side. Is set, the exhaust gas can be collected in the housing 11 from the upstream side to the downstream side. Therefore, for example, when a first exhaust gas path passing through a single purifier is set on the upstream side and a second exhaust gas path passing through a plurality of purifiers is set on the downstream side, the exhaust gas is sent downstream in the housing. In this embodiment, there is no need to provide a distribution pipe in the housing 11, and the number of parts can be reduced and the size can be reduced. Further, in the first space portion 25 and the second space portion 26, the flow of exhaust gas is reversed in the opposite direction, so that an exhaust gas path sufficiently longer than the length of the housing 11 is set in the housing 11. Can do.

(Second Embodiment)
Next, an exhaust gas purification apparatus according to the second embodiment will be described.
In the exhaust gas purifying apparatus according to the second embodiment, the oxidation catalyst 17 is disposed around the SCR catalyst as a set of two.
FIG. 4 shows an exhaust gas purification device 30 according to the second embodiment. Among the components, the same elements as those in the exhaust gas purification device 10 of the first embodiment are referred to the description of the first embodiment. Common symbols are used.

In the exhaust gas purifying apparatus 30 shown in FIG. 4, eight inlet holes 31 are formed in one end wall portion 11A of the housing 11, and an outlet hole 32 is formed in the center of the other end wall portion 11B.
A branch pipe 33 having eight branch pipes 33 </ b> A is provided between the upstream side exhaust pipe 14 and the exhaust gas purification device 10.
Eight oxidation catalysts 17 are installed on the peripheral wall 11 </ b> C side in the housing 11, and an SCR / DPF composite 20 is installed in the center of the housing 11.
The oxidation catalyst 17 is held by a first canning case 34 as a first cover member.
In this embodiment, the oxidation catalyst 17 and the first canning case 34 constitute a first purifier.
An inlet end 34 </ b> A as a first exhaust inlet of the first canning case 34 protrudes from the inlet hole 31 of the housing 11 and is connected to the end of the branch pipe 33.
An outlet end 34 </ b> B as a first exhaust outlet of the first canning case 34 faces the other end wall portion 11 </ b> B of the housing 11.

As shown in FIG. 5, the oxidation catalyst 17 held by the first canning case 34 is a set of two, and each set of oxidation catalyst 17 is adjacent to each other in the circumferential direction of the peripheral wall portion 11C. 17 and spaced apart.
The two first canning cases 34 are in contact with each other such that the oxidation catalyst 17 is parallel to each other.
The first canning case 34 is fixed to the inner surface of the peripheral wall portion 11C by welding.
The first canning case 34 constitutes a first exhaust gas path in which an exhaust gas flows from the inlet end 34A through the oxidation catalyst 17 toward the outlet end 34B.

The DPF 21 and the SCR catalyst 22 are integrated by a second canning case 35 as a second cover member to form the SCR / DPF composite 20.
In this embodiment, the SCR / DPF composite 20 and the second canning case 35 constitute a second purification body.
An inlet end 35A as a second exhaust inlet of the second canning case 35 faces one end wall portion 11A of the housing 11, and an outlet end of the second canning case 35 as a second exhaust outlet is an outlet of the housing 11. It protrudes to the outside from the hole 32 and is connected to the downstream side exhaust pipe 16.
The second canning case 35 is in contact with the first canning case 34 of each surrounding oxidation catalyst 17, and the SCR / DPF composite 20 is held on the center side in the housing 11 by each oxidation catalyst 17 arranged around the second canning case 35. ing.
The second canning case 35 constitutes a second exhaust gas path that serves as an exhaust gas flow from the inlet end 35 </ b> A through the SCR / DPF composite 20 toward the outlet end.

As shown in FIG. 5, two sets of first canning cases 34 that are adjacent to each other in the circumferential direction of the SCR / DPF composite 20 are disposed with a space therebetween.
Therefore, a space defined by the peripheral wall portion 11C, the first canning case 34, and the second canning case 35 is formed between the first canning cases 34 for each set.
This space constitutes a communication passage 36 through which the exhaust gas that has passed through the oxidation catalyst 17 passes to the SCR / DPF composite 20.

A first space 37 is formed between the outlet of the oxidation catalyst 17 in the housing 11 and the end wall 11B.
The first space portion 37 is a space portion defined by the peripheral wall portion 11 </ b> C, the outlet end 34 </ b> B of the first canning case 34, and the second canning case 35, and the outlet of the oxidation catalyst 17 communicates with the inside of the housing 11.
The urea water nozzles 27 installed near the end wall part 11B of the peripheral wall part 11C of the housing 11 are installed corresponding to the number of sets of the oxidation catalyst 17, and in this embodiment, four.

On the other hand, by providing a space between the inlet end 35A of the second canning case 35 and one end wall portion 11A of the housing 11, a second space is formed between the end wall portion 11A and the inlet of the SCR / DPF composite 20. A portion 38 is formed.
The second space 38 is a space defined by the peripheral wall 11 </ b> C, the first canning case 34 and the inlet end 35 </ b> A of the second canning case 35, and the inlet of the SCR / DPF composite 20 communicates with the inside of the housing 11. .

The first space portion 37 communicates with the communication path 36 and guides the exhaust gas to the communication path 36 by reversing the flow direction of the exhaust gas that has passed through the oxidation catalyst 17.
The second space portion 38 communicates with the communication passage 36 and guides the exhaust gas to the SCR / DPF composite 20 by reversing the flow direction of the exhaust gas passing through the communication passage 36 again.
The communication path 36 constitutes an inverted exhaust gas path that serves as an exhaust gas flow from the first space portion 37 communicating with the outlet end 34B toward the second space portion 38 communicating with the inlet end 35A.

In the exhaust gas purification device 30 of this embodiment, the first exhaust gas path of the first canning case 34, the first space 37, the reverse exhaust gas path by the communication path 36, the second space 38, and the second An exhaust gas flow path is formed in the housing 11 by the second exhaust gas path of the canning case 35.
According to this embodiment, since the first canning case 34 that contacts the second canning case 35 is larger than in the first embodiment, the SCR / DPF composite 20 by the oxidation catalyst 17 on the center side in the housing 11 is used. Is more stable.
Further, since there are many first canning cases 34 that come into contact with the second canning case 35, the amount of heat transferred from the oxidation catalyst 17 to the SCR / DPF composite 20 can be increased.

(Third embodiment)
Next, an exhaust gas purification apparatus according to a third embodiment will be described.
The exhaust gas purifying apparatus according to the third embodiment is different from the first and second embodiments in the structure of the housing, the oxidation catalyst, the canning case, and the SCR / DPF composite.
FIG. 6 is a cross-sectional view showing a cross-section of the exhaust gas purifying device 40 according to the third embodiment.

The housing 41 of the exhaust gas purification device 40 shown in FIG. 6 is a hollow rectangular parallelepiped.
An inlet hole (not shown) is formed in one end wall portion of the housing 41, and an outlet hole (not shown) is formed in the other end wall portion.
A cylindrical SCR catalyst 44 is located in the center of the housing 41, and an oxidation catalyst 42 that holds the SCR catalyst 44 is disposed on both sides of the SCR catalyst 44.
The SCR catalyst 44 includes a catalyst carrier that supports a catalyst having an exhaust gas purification function, and does not include a canning case as in the first and second embodiments.

The oxidation catalyst 42 of this embodiment has an exhaust gas purification function.
The outer peripheral surface of the oxidation catalyst 42 is formed by four surfaces, three of which are flat surfaces, and the remaining one surface is an arc surface that follows the outer peripheral surface of the SCR catalyst 44.
The outer periphery of the oxidation catalyst 42 is covered with a canning case 43 as a cover member.
The canning case 43 shown in FIG. 6 is fixed to the peripheral wall portion 41 </ b> A of the housing 41 by welding, and an arc portion 43 </ b> A that follows the arc surface of the oxidation catalyst 42 in the canning case 43 contacts the outer peripheral surface of the SCR catalyst 44.
Therefore, the SCR catalyst 44 is held by the oxidation catalyst 42 on both sides and held on the center side in the housing 41.
Since the arc portion 43A of the canning case 43 is in contact with 1/4 or more of the outer periphery of the SCR catalyst 44, the two canning cases 43 cover more than half of the outer periphery of the SCR catalyst 44, and the SCR catalyst 44 is in the canning case. It will not drop out of 43.

An inlet end (not shown) as a first exhaust inlet of the oxidation catalyst 42 protrudes from an inlet hole of the housing 41, and this inlet end is a branch of a branch pipe (not shown) for branching exhaust gas from the engine. Connected with tube.
Further, the outlet end (not shown) as the first exhaust outlet of the oxidation catalyst 42 faces the other end wall portion of the housing 41 and communicates with the inside of the housing 41.
An inlet end (not shown) as a second exhaust inlet of the SCR catalyst 44 is opposed to one end wall portion of the housing 41 and communicates with the inside of the housing 41, and serves as a second exhaust outlet of the SCR catalyst 44. An outlet end (not shown) protrudes from the outlet hole.
In the exhaust gas purification apparatus 40 according to this embodiment, although not shown, the first space portion (not shown) corresponding to the first space portion 25 of the first embodiment is an outlet of the canning case 43 in the housing 41. It is formed between the end and the other end wall portion of the housing 41.
Further, a second space portion (not shown) corresponding to the second space portion 26 of the first embodiment is formed between one end wall portion of the housing 41 and the inlet end of the SCR catalyst.

In this embodiment, as shown in FIG. 6, the two oxidation catalysts 42 and the SCR catalyst 44 that sandwich the SCR catalyst 44 divide the space in the housing 41. That is, the space in the housing 41 is defined by the inner wall of the housing 41, the outer peripheral surface of the oxidation catalyst 42, and the outer peripheral surface of the SCR catalyst 44.
The two divided spaces constitute a communication passage 45, and the communication passage 45 is formed between the outlet end of the canning case 43 and the other end wall of the housing 41 and one of the housing 41 and the second space. The first space portion formed between the end wall portion of the SCR catalyst 44 and the inlet end of the SCR catalyst 44 is communicated.
Near one end wall portion of the peripheral wall portion 41A of the housing 41 on the first exhaust outlet side of the communication passage 45, a urea water nozzle (not shown) as an additive injection valve passes the nozzle end to the first space portion. Is installed.
In this embodiment, urea water nozzles are installed corresponding to the number of oxidation catalysts 42, and the urea water nozzles inject urea water for the SCR catalyst as an additive.
Accordingly, the first space portion formed between the outlet end of the canning case 43 and the other end wall portion of the housing 41 reverses the flow of the exhaust gas that has passed through the oxidation catalyst 42, and the urea water nozzle It functions as a space for mixing urea water injected into the exhaust gas that has passed through the oxidation catalyst 42.

In the exhaust gas purification device 40 of this embodiment, the exhaust gas that has exited the first space through the oxidation catalyst 42 in the canning case 43 reverses the flow direction in the first space and passes through the communication passage 45. .
The exhaust gas that has passed through the communication passage 45 reverses the flow direction in the second space on the inlet end side of the SCR catalyst 44 and passes through the SCR catalyst 44.

According to this embodiment, the SCR catalyst 44 is sandwiched between the two canning cases 43 provided with the arc portions 43 </ b> A following the outer peripheral surface of the SCR catalyst 44 and held on the center side in the housing 41. Excessive deformation due to thermal expansion can be suppressed by pressing the SCR catalyst 44 of the canning case 43.
The arcuate portion 43A of the canning case 43 is provided so as to cover 1/4 or more of the outer peripheral surface of the SCR catalyst 44. Even if there are only two canning cases 43, the canning case 43 makes the SCR catalyst 44 more The housing 41 can be reliably and stably held on the center side.
Further, since the arc portion 43A of the canning case 43 is provided so as to cover 1/4 or more of the outer peripheral surface of the SCR catalyst 44, heat transfer from the oxidation catalyst 42 to the SCR catalyst 44 is easy. Heat dissipation of the SCR catalyst 44 can be suppressed.

(Fourth embodiment)
Next, an exhaust gas purification apparatus according to a fourth embodiment will be described.
The exhaust gas purifying apparatus according to the fourth embodiment is different from the first and second embodiments in the structure of the housing, the oxidation catalyst, the canning case, and the SCR / DPF composite.
FIG. 7 is a cross-sectional view showing a transverse cross section of the exhaust gas purifying apparatus 40 according to the fourth embodiment.

The housing 51 of the exhaust gas purification device 50 shown in FIG. 7 is a hollow rectangular parallelepiped.
Although not shown, a plurality of inlet holes are formed in one end wall portion of the housing 51, and one outlet hole is formed in the other end wall portion.
A cylindrical SCR catalyst 56 is located in the center of the housing 51, and a large-diameter oxidation catalyst 52 and a small-diameter oxidation catalyst 54 that hold the SCR catalyst 56 are disposed around the SCR catalyst 56.

The large-diameter oxidation catalyst 52 and the small-diameter oxidation catalyst 54 of this embodiment differ only in the diameter dimension, and the diameter dimension of the large-diameter oxidation catalyst 52 is set larger than the diameter dimension of the small-diameter oxidation catalyst 54.
The large diameter oxidation catalyst 52 is fixed in a large diameter canning case 53 as a first cover member, and the small diameter oxidation catalyst 54 is fixed in a small diameter canning case 55 as another first cover member.
A large diameter canning case 53 and a small diameter canning case 55 shown in FIG. 7 are fixed to the housing 51 by welding.
The large-diameter oxidation catalyst 52 and the small-diameter oxidation catalyst 54 are alternately arranged around the SCR catalyst 56, the large-diameter oxidation catalyst 52 is located on the corner side in the housing 51, and the small-diameter oxidation catalyst 54 is in the corner in the housing 51. Located between the corners.

The SCR catalyst 56 is fixed in an SCR canning case 57 as a second cover member, and the SCR canning case 57 contacts the large diameter canning case 53 and the small diameter canning case 55.
Therefore, the SCR catalyst 56 is held on the center side in the housing 51 by contact with the large diameter oxidation catalyst 52 and the small diameter oxidation catalyst 54.

An inlet end (not shown) as a first exhaust inlet in the large diameter oxidation catalyst 52 and the small diameter oxidation catalyst 54 protrudes from a plurality of inlet holes of the housing 51, and these inlet ends receive exhaust gas from the engine. It connects with the branch pipe of the branch pipe (not shown) which branches.
The outlet ends of the large-diameter oxidation catalyst 52 and the small-diameter oxidation catalyst 54 as the first exhaust outlet face the other end wall portion of the housing 51 and communicate with the inside of the housing 51.
The inlet end of the SCR catalyst 56 communicates with the inside of the housing 51 so as to face one end wall portion of the housing 51, and the outlet end of the SCR catalyst 56 protrudes from the outlet hole.

In the exhaust gas purifying apparatus 50 according to this embodiment, although not shown, the first space portion corresponding to the first space portion 25 of the first embodiment includes a large diameter canning case 53 and a small diameter canning case 55 in the housing 51. Is formed between the outlet end of the housing 51 and the other end wall portion of the housing 51.
A second space corresponding to the second space 26 of the first embodiment is formed between one end wall of the housing 51 and the inlet end of the SCR catalyst 56.

In this embodiment, as shown in FIG. 7, the large diameter oxidation catalyst 52, the small diameter oxidation catalyst 54, and the SCR catalyst 56 divide the space in the housing 51.
Each space formed by the division constitutes a communication path 58, and the communication path 58 is formed between the outlet end of the large diameter canning case 53 and the small diameter canning case 55 and the other end wall portion of the housing 51. The first space portion communicates with a second space portion formed between one end wall portion of the housing 51 and the inlet end of the SCR catalyst 56.

In the exhaust gas purification device 50 of this embodiment, the exhaust gas that has flowed into the first space through the large-diameter oxidation catalyst 52 in the large-diameter canning case 53 or the small-diameter oxidation catalyst 54 in the small-diameter canning case 55 is the first The direction of flow is reversed in the space and passes through the communication path 58.
The exhaust gas passing through the communication path 58 reverses the flow direction in the second space on the inlet end side of the SCR catalyst 56 and passes through the SCR catalyst 56.

According to this embodiment, since the SCR catalyst 56 is held by the large-diameter oxidation catalyst 52 and the small-diameter oxidation catalyst 54 having different diameter dimensions, the cross-sectional area of the communication passage 58 can be reduced. Further, the heat dissipation of the SCR catalyst 56 can be suppressed.
In addition, since the large-diameter oxidation catalyst 52 and the small-diameter oxidation catalyst 54 are alternately arranged around the SCR catalyst 56, it is possible to suppress an uneven temperature distribution of the SCR catalyst 56 due to heat radiation.

(Fifth embodiment)
Next, an exhaust gas purification apparatus according to a fifth embodiment will be described.
In the exhaust gas purification apparatus of the fifth embodiment, the first purification body is an oxidation catalyst, the second purification body is a DPF, and the additive injection valve is a fuel injection valve that injects regenerated fuel. Different from the configuration of the embodiment.
About the element which is common in 1st Embodiment, in addition to using description of 1st Embodiment, a code | symbol is used in common.

FIG. 8 is a cross-sectional view showing a cross section of an exhaust gas purifying apparatus 60 according to the fifth embodiment.
In the housing 11 of the exhaust gas purification device 60, four oxidation catalysts 17 installed on the peripheral wall portion 11C side and a DPF 61 installed in the center of the housing 11 are accommodated.
In this embodiment, no SCR catalyst is provided in the housing 11.
The DPF 61 includes a honeycomb filter formed by extrusion, and the DPF 61 corresponds to a second purifier having a purifying function of collecting PM in the exhaust gas and purifying the exhaust gas.

The periphery of the DPF 61 of this embodiment is covered with a second canning case 62 as a second cover member.
The second canning case 62 is in contact with the first canning case 18 of each surrounding oxidation catalyst 17, and the DPF 61 is held on the center side in the housing 11 by each oxidation catalyst 17 arranged around.
The DPF 61 is disposed in the center of the housing 11, one end of the second canning case 62 is an inlet end 62 </ b> A as a second exhaust inlet, and the inlet end 62 </ b> A faces one end wall portion 11 </ b> A of the housing 11. Yes.
The other end of the second canning case 62 is an outlet end 62B as a second exhaust outlet, and the outlet end 62B protrudes outside from the outlet hole 13 of the housing 11 and is connected to the downstream exhaust pipe 16. .
The second canning case 62 constitutes a second exhaust gas path in which an exhaust gas flows from the inlet end 62A through the DPF 61 toward the outlet end 23B.

Near the end wall portion 11B of the peripheral wall portion 11C of the housing 11 on the first exhaust outlet side of the communication passage 24, a fuel injection nozzle 63 as an additive injection valve is installed with the nozzle end directed toward the first space portion 25. ing.
In this embodiment, the fuel injection nozzles 63 are installed corresponding to the number of oxidation catalysts 17.
The fuel injection nozzle 63 is connected via a pipe to a fuel pump 64 that pumps DPF regeneration fuel as an additive from the fuel tank 65 to the fuel injection nozzle 63.
Accordingly, the first space 25 is a space for reversing the flow of the exhaust gas that has passed through the oxidation catalyst 17 and for mixing the fuel injected into the exhaust gas that has passed through the oxidation catalyst 17 by the fuel injection nozzle 63. Function.

According to the exhaust gas purification apparatus of this embodiment, when PM accumulates on the DPF 61, the fuel for DPF regeneration is injected from the fuel injection nozzle 63 toward the first space portion 25.
The injected fuel is heated and dispersed in the exhaust gas while passing through the communication passage 24, and when passing through the DPF 61, PM is burned and removed, whereby the DPF 61 can be regenerated.

The exhaust gas purifying apparatus according to each of the above embodiments shows one embodiment of the present invention, and the present invention is not limited to each of the above embodiments, and the invention is as follows. Various changes are possible within the scope of the gist.
In the above-described first, second, fourth, and fifth embodiments, the first purification body is held by the first purification body by contacting the first canning case and the second canning case. The first canning case and the second canning case may be bonded by welding or the like, and the second purifier may be held by the first purifier by bonding. In this case, it is possible to hold the second purification body in the housing more reliably than in the case of only contact.
In the above first and second embodiments, the SCR / DPF composite in which the SCR catalyst and the DPF are integrated is used as the second purification body. However, the second purification body is the same as in the third and fourth embodiments. The SCR catalyst alone or the DPF alone as in the fifth embodiment may be used. When the second purifier is the SCR catalyst alone, the additive injection valve is preferably a reducing agent injection valve that injects a reducing agent. Moreover, when it is a SCR / DPF composite and a 2nd purification body is DPF, it is preferable that an additive injection valve is a fuel injection valve. In the case of the SCR / DPF composite, a reducing agent injection valve as an additive injection valve and a fuel injection valve may be provided close to each other.
In the first, second, and fifth embodiments, the additive injection valve is provided on the peripheral wall portion of the housing. However, the additive injection valve is not limited to the peripheral wall portion, and may be provided on the end wall portion of the housing. The number and position of the additive injection valve may be set according to the additive addition conditions.
In the first, second, fourth, and fifth embodiments, the first and second purification bodies have a circular cross-sectional shape. However, the cross-sectional shapes of the first and second purification bodies are particularly circular. It is not limited. The cross-sectional shape of the first purification body and the second purification body may be, for example, a polygon, an ellipse, or an ellipse, and can be freely set.

10, 30, 40, 50, 60 Exhaust gas purification device 11, 41, 51 Housing 17, 42 Oxidation catalyst (first purification body)
18, 34 First canning case (first cover member)
18A, 34A inlet end (first exhaust inlet)
18B, 34B Outlet end (first exhaust outlet)
20 SCR / DPF composite 21 DPF
22, 44, 56 SCR catalyst (part or all of the second purifier)
23, 35 Second canning case (second cover member)
23A, 35A inlet end (second exhaust inlet)
23B Outlet end (second exhaust outlet)
24, 36, 45, 58 Communication path 25, 37 First space 26, 38 Second space 27 Urea water nozzle (additive injection valve)
43 Canning Case (Cover Member)
52 Large-diameter oxidation catalyst (first purification body)
53 Large diameter canning case (first cover member)
54 Small-diameter oxidation catalyst (first purifier)
55 Small diameter canning case (first cover member)
57 SCR canning case (second cover member)
61 DPF (2nd purification body)
62 Second canning case (second cover member)
63 Fuel injection nozzle (additive injection valve)

Claims (8)

A plurality of first purification bodies for purifying exhaust gas discharged from the internal combustion engine;
A second purification body for purifying exhaust gas after passing through the plurality of first purification bodies;
In an exhaust gas purification apparatus comprising a plurality of the first purification bodies and a housing in which the second purification bodies are accommodated,
The plurality of first purification bodies are disposed in contact with the outer peripheral surface of the second purification body and with an interval between the first purification bodies,
The second purification body is held at a distance from the inner wall of the housing via the plurality of first purification bodies,
A communication path is formed by being partitioned by the inner wall of the housing, the outer peripheral surface of the first purification body, and the outer peripheral surface of the second purification body,
The first purifier includes a first exhaust inlet connected to the inlet of the housing, and a first exhaust outlet located on the opposite side of the first exhaust inlet and communicating with the communication path,
The second purification body includes a second exhaust inlet communicating with the communication path, and a second exhaust outlet connected to the outlet of the housing,
An exhaust gas purifying apparatus, wherein an additive injection valve for injecting an additive to the exhaust gas emitted from the first exhaust outlet is installed.   A first space part between the first exhaust outlet and the communication path; a second space part between the second exhaust inlet and the communication path; 2. The exhaust gas purifying apparatus according to claim 1, wherein the flow of the exhaust gas is reversed in the opposite direction in the two spaces.   The exhaust gas purification device according to claim 1 or 2, wherein the second purification body is held by pressing the second purification body by a plurality of the first purification bodies. The first purification body includes a cover member that covers the periphery thereof,
The exhaust gas purification device according to claim 3, wherein the second purification body is pressed by contact with the cover member.   The exhaust gas purifying apparatus according to claim 1 or 2, wherein the second purifying body is held by adhesion with a plurality of the first purifying bodies. The first purification body includes a first cover member that covers the periphery thereof,
The second purification body includes a second cover member that covers the periphery thereof,
The exhaust gas purification device according to claim 5, wherein the second purification body is held by adhesion between the first cover member and the second cover member. The first purification body is an oxidation catalyst;
The second purification body is an SCR catalyst, or an SCR catalyst and a DPF,
The exhaust gas purifying device according to claim 6, wherein the additive is a reducing agent for an SCR catalyst. The first purification body is an oxidation catalyst;
The second purification body is DPF, or DPF and SCR catalyst,
The exhaust gas purifying device according to claim 6, wherein the additive is a fuel for regeneration of the DPF.

Images