JP2010242704A - Purifier of exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purifier of exhaust gas for purifying the exhaust gas of an internal combustion engine using an aqueous solution of urea capable of effectively accelerating the mixing between the exhaust gas and urea while maintaining its compact configuration. <P>SOLUTION: A urea aqueous solution circulator 110 for circulating a urea aqueous solution is provided to the exhaust pipe 150 of an internal combustion engine 120. The urea aqueous solution circulator 110 comprises an injection portion 10, a urea aqueous solution tank 111, an injection pump (injector) 112, a recovery pump 113 and a piping 114 for urea aqueous solution. The injection portion 10 comprises an injection port (flow-in port) 11 through which the urea aqueous solution is injected and a recovery port 12 through which the injected urea aqueous solution is recovered. The recovery port 12 is a port through which the urea aqueous solution delivered in the exhaust pipe 150 is recovered from the exhaust pipe 150 into the piping 114 (recovery-side piping 114b) for the urea aqueous solution. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device, and more particularly to an apparatus for purifying exhaust gas of an internal combustion engine using a reducing agent.

A urea SCR (Selective Catalytic Reduction) system is known as a purification device for purifying exhaust gas from a vehicle. The urea SCR system is used as an exhaust gas aftertreatment system for an internal combustion engine such as a diesel engine. Using urea and ammonia generated from urea as a reducing agent, NOx (nitrogen oxide) discharged from the internal combustion engine is reduced to N ₂ (nitrogen) and H ₂ O (water), thereby removing NOx. The exhaust gas is purified.

  The urea SCR system promotes the reduction reaction by uniformly mixing urea with exhaust gas and bringing it into contact with the SCR catalyst. Here, as a problem of the urea SCR system, there is a point how urea is mixed with exhaust gas uniformly. If not uniformly mixed, unreacted ammonia is discharged to the atmosphere (ammonia slip), or unreacted NOx remains, resulting in insufficient purification.

In order to solve this problem, two methods have been conventionally employed. The first point is a method of injecting urea from about 2 m upstream of the SCR catalyst in order to increase the mixing time of urea and exhaust gas. This is a method used in a truck or the like that can take a lot of in-vehicle space.
The second point is a method of providing a structure that promotes mixing of urea and exhaust gas. For example, a turbulent flow is actively generated in the exhaust pipe using a mixer, an injection nozzle is arranged in the center of the exhaust pipe, a perforated plate is arranged in the exhaust pipe, the exhaust gas is heated, and the exhaust gas exceeds A measure such as emitting a sound wave is taken. Patent Document 1 discloses an example of such a method. The configuration of Patent Document 1 includes an addition nozzle that is connected to an air compressor and injects urea water, a throttle portion that restricts the flow of exhaust gas, and a diffusion plate that promotes mixing.

JP 2006-132393 A

However, the conventional technique has a problem that the configuration for promoting mixing cannot be made compact.
For example, the method of injecting urea from about 2 m upstream of the SCR catalyst increases the overall structure and cannot be used for passenger cars. Further, in the method of providing a structure that promotes mixing of urea and exhaust gas, a mixer, a diffusion plate, and the like are required, so that it is necessary to secure a space.

  The present invention has been made to solve such problems, and has an exhaust gas purification device that can efficiently promote mixing of exhaust gas and a reducing agent while having a compact configuration. The purpose is to provide.

  An exhaust gas purification apparatus according to the present invention is an exhaust gas purification apparatus that purifies exhaust gas of an internal combustion engine using urea water, and has an inlet for circulating urea water in an exhaust path through which the exhaust gas passes. A recovery port for recovering the distributed urea water from the exhaust path, and a urea water circulation device for circulating the urea water through the recovery port and the inflow port.

  Since this exhaust gas purification device includes a recovery port for recovering urea water from the exhaust path, urea water can be supplied over the entire exhaust path, and mixing of exhaust gas and urea can be performed efficiently. Can be promoted. Further, it is not necessary to provide a complicated structure such as a mixer or a diffusion plate in the exhaust pipe.

The urea water circulation device may include an injection device that injects urea water, and the inflow port may be an injection port that injects urea water.
The injection port may inject urea water toward the recovery port.
The injection port includes a first injection port that injects urea water in a first direction, and a second injection port that injects urea water in a second direction that is different from the first direction. The port may be provided downstream of the first injection port and the second injection port in the exhaust path. If it does in this way, the quantity of the urea which is injected from each injection port and vaporizes will become mutually complementary, and urea can be mixed uniformly.
A first injection port group including a plurality of first injection ports and a second injection port group including a plurality of second injection ports are provided, and the first injection port group and the second injection port group are opposed to each other in the exhaust path. The first injection port and the second injection port may be provided at positions that do not oppose each other in the exhaust path. If it does in this way, urea can be mixed uniformly to the whole exhaust gas.
The first direction and the second direction are directions opposite to each other, and the injection port is configured to inject urea water in a third direction orthogonal to the first direction, and urea water. And a fourth injection port that injects in a fourth direction that is opposite to the third direction. The third injection port and the fourth injection port are the first injection port and the second injection port in the exhaust path. The recovery port may be provided on the downstream side of the first injection port, the second injection port, the third injection port, and the fourth injection port in the exhaust path. If it does in this way, the quantity of the urea which is injected from each injection port and vaporizes will become mutually complementary, and urea can be mixed uniformly.

A support member that is provided in the exhaust path and transfers the inlet and the recovery port may be provided, and at least a part of the urea water may flow along the support member. If it does in this way, the range which urea water distribute | circulates will become wide, and urea can be vaporized more efficiently.
The support member may be a metal net.

The exhaust path or the recovery port may include a reflecting surface that splashes the injected urea water into the exhaust path to diffuse the splashes. If it does in this way, mixing can be accelerated | stimulated by the fine droplet bounced back.
The recovery port may include a non-reflective portion that does not bounce the injected urea water back into the exhaust path. In this way, mixing can be accurately controlled.
The non-reflecting part may include at least one of a large depth collecting part in which the depth from the exhaust path of the collecting port is increased, a tapered surface that guides the urea water so as not to rebound, and a shielding part that shields the splash of urea water. .

The exhaust gas purification device includes a selective reduction catalyst,
The inlet is provided upstream of the selective reduction catalyst in the exhaust path,
The selective reduction catalyst may promote a reduction reaction by urea or ammonia generated from urea water and nitrogen oxides in the exhaust gas.

  Since the exhaust gas purifying apparatus according to the present invention includes a recovery port for recovering urea water from the exhaust path, the urea water can be supplied over the entire exhaust path, and the exhaust gas and the exhaust gas can be supplied in a compact configuration. Mixing with urea can be promoted efficiently.

It is a figure which shows the structure containing the purification apparatus of the exhaust gas which concerns on this invention. 3 is a cross-sectional view illustrating a configuration of an injection unit according to Embodiment 1. FIG. 3 is a cross-sectional view illustrating a configuration of an injection unit according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view illustrating a configuration of a distribution unit according to Embodiment 2. FIG. 6 is a cross-sectional view illustrating a configuration of a distribution unit according to Embodiment 2. FIG. 6 is a cross-sectional view illustrating a configuration of an injection unit according to Embodiment 3. 6 is a schematic cross-sectional view showing a configuration of an injection unit according to Embodiment 3. FIG. 6 is a schematic cross-sectional view showing a configuration of an injection unit according to Embodiment 4. FIG. FIG. 10 is a schematic cross-sectional view showing a configuration of an injection unit according to a modification of the fourth embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of an injection unit according to a fifth embodiment. FIG. 10 is a schematic cross-sectional view illustrating a configuration of an injection unit according to Embodiment 5. 10 is a schematic cross-sectional view showing a configuration of an injection unit according to Embodiment 6. FIG. FIG. 10 is a schematic cross-sectional view illustrating a configuration of an injection unit according to a modification of the sixth embodiment. FIG. 10 is a cross-sectional view illustrating an example of a configuration of a recovery port according to a seventh embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of a recovery port according to a modification example of the seventh embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of a recovery port according to a modification example of the seventh embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of a recovery port according to a modification example of the seventh embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a configuration including an exhaust gas purification apparatus 100 according to the present invention. The purification device 100 is provided in the exhaust system of the internal combustion engine 120 and purifies the exhaust gas of the internal combustion engine 120 using urea water as a reducing agent. The internal combustion engine 120 is, for example, a diesel engine, which burns fuel in a cylinder and discharges the exhaust gas to an exhaust system. The exhaust gas contains NOx (nitrogen oxide), and the purification device 100 removes this NOx by a reducing action.

  The exhaust system of the internal combustion engine 120 is provided with an exhaust pipe 150 as an exhaust path. The exhaust gas passes through the exhaust pipe 150 and is discharged to the outside (for example, the atmosphere). The exhaust pipe 150 is provided with a DPF (Diesel Particulate Filter) 130 for removing PM (particulate matter) contained in the exhaust gas. Further, the purification device 100 includes an SCR catalyst (selective reduction catalyst) 140 that is a catalyst that promotes a reduction reaction of urea and ammonia with NOx in the exhaust pipe 150 downstream of the DPF 130. The exhaust gas flows into the exhaust pipe 150 from the internal combustion engine 120 and is discharged to the outside through the DPF 130 and the SCR catalyst 140. That is, the exhaust gas flows in the direction of arrow A in the exhaust pipe 150.

  In the exhaust pipe 150, the injection unit 10 that causes urea water to flow through the exhaust pipe 150 is provided at a position downstream of the DPF 130 and upstream of the SCR catalyst 140. Urea vaporized from the urea water and ammonia generated from the urea act as a reducing agent for reducing NOx in the SCR catalyst 140. In the following, only urea is exemplified as the reducing agent generated from urea water, but ammonia is also generated from urea water or urea and acts as a reducing agent.

  A urea water circulation device 110 is provided as a device for supplying urea water to the injection unit 10. In addition to the injection unit 10, the urea water circulation device 110 includes a urea water tank 111 that stores urea water, an injection pump (injection device) 112 that boosts pressure to inject the urea water into the exhaust pipe 150, and urea water. A recovery pump 113 for recovering from the exhaust pipe 150 and a urea water pipe 114 which is a pipe connecting them are provided. The injection pump 112 raises the urea water to a predetermined supply feed pressure, and pumps it to the injection unit 10.

2 and 3 are cross-sectional views illustrating the configuration of the injection unit 10. 2 is a cross-sectional view along the axis of the exhaust pipe 150, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, that is, a cross section perpendicular to the axis of the exhaust pipe 150. It is assumed that the exhaust gas flows in the direction of arrow A.
The injection unit 10 includes an injection port (inlet) 11 for injecting urea water and a recovery port 12 for recovering the injected urea water. The injection port 11 is provided upstream of the SCR catalyst 140, and injects urea water from the urea water pipe 114 (supply side pipe 114a) into the exhaust pipe 150 to circulate. The injection port 11 is a small hole, for example, and injects urea water pressurized by the injection pump 112 as a jet 13. Thus, the injection port 11 has a simple configuration and does not require a complicated structure such as a nozzle or a solenoid valve.

The recovery port 12 recovers urea water flowing through the exhaust pipe 150 from the exhaust pipe 150 to the urea water pipe 114 (recovery side pipe 114b). Here, the injection port 11 and the recovery port 12 are provided facing the inside of the exhaust pipe 150, and the injection port 11 injects the jet 13 toward the recovery port 12. For example, the injection port 11 is provided on the inner wall on the vertical upper side of the exhaust pipe 150, and the recovery port 12 is provided on the inner wall on the lower vertical side of the exhaust pipe 150. Such a positional relationship is efficient because the direction of the jet 13 follows the direction of gravity. However, such a positional relationship is not necessary as long as the ejection port 11 and the recovery port 12 are provided to face each other.
When the jet 13 is deflected by the flow of exhaust gas or gravity, the location of the recovery port 12 can be changed as appropriate according to the deflection state.

  As shown in FIG. 1, the urea water recovered from the recovery port 12 is pumped to the urea water tank 111 by the recovery pump 113. That is, the urea water circulation device 110 circulates the urea water through the urea water tank 111, the injection pump 112, the supply side piping 114a, the injection port 11, the recovery port 12, the recovery side piping 114b, and the recovery pump 113 in this order. .

As shown in FIGS. 2 and 3, when the jet 13 injected from the injection port 11 passes through the exhaust pipe 150, urea contained in the jet 13 is vaporized and mixed with the exhaust gas.
The jet 13 is agitated by the exhaust gas, and a part thereof becomes a fine droplet 13 a and is separated from the jet 13. This stirring action includes a shearing action by the exhaust gas and an action by the wake flow when the exhaust gas passes through the liquid of the jet 13. Since the liquid droplet 13a has a small mass and a small mass compared to its surface area, the liquid droplet 13a floats in the exhaust gas and passes through the exhaust pipe 150 together with the exhaust gas toward the SCR catalyst 140. Even in this process, urea is vaporized from the droplet 13a.

Here, since the exhaust gas includes a large number of minute droplets 13a, it is possible to efficiently generate urea and uniformly mix the generated urea with the exhaust gas. That is, the mixing of exhaust gas and urea can be promoted efficiently.
Further, since the portion of the jet 13 that has not been separated as the droplet 13a reaches the recovery port 12 and is recovered, it is possible to prevent ammonia slip while circulating urea water throughout the exhaust pipe 150. And mixing of exhaust gas and urea can be promoted efficiently.

  When the exhaust gas mixed with urea reaches the SCR catalyst 140, the SCR catalyst 140 promotes a reduction reaction between urea as a reducing agent and NOx in the exhaust gas, thereby removing NOx. In this way, the purification device 100 purifies the exhaust gas.

In the first embodiment described above, at least a part of the exhaust pipe 150 is provided between the DPF 130 and the SCR catalyst 140, whereby the DPF 130 and the SCR catalyst 140 are arranged separately. The DPF 130, the injection unit 10, and the SCR catalyst 140 may be disposed in the same casing. That is, an outer wall such as a casing forming a single space may be provided, and the DPF 130, the injection unit 10, and the SCR catalyst 140 may be arranged in this order from the upstream in this single space.
Even in such a configuration, since the mixing of the exhaust gas and urea is efficiently performed by the injection unit 10, it is necessary to make the distance between the injection unit 10 and the SCR catalyst 140 long as in the prior art. In addition, the size of the casing can be reduced.

When urea is injected from a nozzle as in the prior art, there is a problem that urea flows on the downstream side along the flow of exhaust gas before it diffuses throughout the exhaust passage. On the other hand, according to Embodiment 1 of the present invention, a large amount of urea water can be injected toward the recovery port 12, so that urea water can be supplied over the entire exhaust pipe 150. As a result, Urea water can be diffused throughout the exhaust passage. Therefore, the purification apparatus 100 according to Embodiment 1 can efficiently promote mixing.
Moreover, since the injection port 11 and the collection port 12 are provided facing the inside of the exhaust pipe 150, the space can be particularly reduced.

In the first embodiment, the recovery port 12 is provided on the gravity direction side, that is, on the lower side when viewed from the inflow port 11. For this reason, the urea water is not pressurized and sprayed in the form of a mist using an injection device as in the prior art, but the urea water can be simply flowed into the exhaust pipe 150 without being pressurized. For example, the urea water can be supplied continuously from the inlet 11 to the recovery port 12. That is, the urea water is in a state of being continuous as a liquid from the inlet 11 to the recovery port 12. Alternatively, the urea water is in a state where it is not divided as a liquid from the inlet 11 to the recovery port 12. Alternatively, the hydrogen bonds of water molecules in the urea water are continuous from the inlet 11 to the recovery port 12.
Therefore, in Embodiment 1, the injection device which pressurizes urea water is unnecessary, and the configuration becomes compact.
The recovery port 12 does not have to be provided strictly in the direction of gravity as viewed from the inflow port 11, and may be a position where urea water guided by gravity can reach.

In the first embodiment described above, the recovery pump 113 is provided. However, if the urea water tank 111 is disposed on the gravity direction side (lower side) of the recovery port 12, the recovery pump 113 may not be provided. .
Further, in the first embodiment, the injection pump 112 pressurizes and feeds the urea water. However, this may be any pump that pumps the urea water so that the urea water flows out from the injection port 11. You may not perform.

  In the first embodiment, urea water is used as the reducing agent, but ammonia water may be used instead of urea water. That is, ammonia water may be circulated instead of urea water (or in addition to urea water). However, since it is necessary to recover the reducing agent from the recovery port 12, it is not preferable to use a gas phase reducing agent, and the reducing agent is limited to a liquid phase.

Embodiment 2. FIG.
In Embodiment 1, the urea water was circulated through the exhaust pipe 150 by injecting the urea water as the jet 13 in the injection unit 10. In the second embodiment, instead of the injection unit 10, a circulation unit that hangs urea water on a wire mesh and supplies it to the exhaust pipe 150 is provided. Hereinafter, differences from the first embodiment will be described.
4 and 5 are cross-sectional views illustrating the configuration of the circulation unit 20 that causes the urea water to flow through the exhaust pipe 150. 4 is a cross-sectional view along the axis of the exhaust pipe 150, and FIG. 5 is a cross-sectional view taken along the line VV in FIG. 4, that is, a cross section perpendicular to the axis of the exhaust pipe 150. It is assumed that the exhaust gas flows in the direction of arrow A.

  The circulation unit 20 includes a wire mesh 24 provided across the inlet 21 and the recovery port 22. The wire mesh 24 is a flow guide member that guides the flow of urea water from the inlet 21 to the recovery port 22. The metal mesh 24 is provided in the exhaust pipe 150, and at least part of the urea water flowing into the exhaust pipe 150 from the inlet 21 forms a urea water flow 23 that flows along the metal mesh 24 and flows to the recovery port 22. become. Here, since the urea water flow 23 flows along the wire mesh 24, there is no need to increase the discharge pressure of the injection pump 112, and the urea water is reliably guided to the recovery port 22 by the weak pressure of the urea water to the circulation part 20. be able to.

  When the urea water flow 23 flowing in from the inlet 21 passes through the exhaust pipe 150, urea contained in the urea water flow 23 is vaporized and mixed with the exhaust gas. Further, the urea water stream 23 is agitated by the exhaust gas in the same manner as the jet 13 in the first embodiment, and a part of the urea water stream 23 is separated from the urea water stream 23 as a minute droplet 23a, and urea is vaporized therefrom. . Further, the wire mesh 24 has a shape in which a plurality of wires extending in directions orthogonal to each other intersect as shown in FIG. 5, and the urea water flow 23 can be guided not only in the vertical direction but also in the horizontal direction. Urea can be vaporized more efficiently by widening the expanding range. This urea acts as a reducing agent and reduces NOx.

  In the second embodiment described above, the metal mesh 24 is a metal mesh. However, the metal mesh 24 may not be a metal as long as it is a flow guide member that has the function of guiding urea water from the inlet 21 to the recovery port 22. Further, a stainless steel net may be used instead of the metal net 24, or a non-metallic net may be used. In the second embodiment, the wire mesh 24 includes a vertical wire and a horizontal wire, but the direction in which the wire extends is not limited thereto. For example, it may consist of a wire extending from the upper left to the lower right and a wire extending from the upper right to the lower left. Further, the wire may be provided only in one direction, for example, only the wire in the vertical direction may be provided.

Embodiment 3 FIG.
In Embodiments 1 and 2, urea water was circulated only in one direction. In Embodiment 3, urea water is circulated in two directions. Hereinafter, differences from the first embodiment will be described.
FIG. 6 is a cross-sectional view showing a configuration of the injection unit 30 that causes the urea water to flow through the exhaust pipe 150, and is a cross section perpendicular to the axis of the exhaust pipe 150. FIG. 7 is a schematic cross-sectional view schematically showing a cross section along the axis of the exhaust pipe 150. It is assumed that the exhaust gas flows in the direction of arrow A.

The injection unit 30 includes a plurality of first injection ports 31 and a plurality of second injection ports 32 as injection ports for injecting urea water. The plurality of first injection ports 31 are provided at equal intervals from each other, and each injects urea water in the direction B (first direction). The plurality of second injection ports 32 are provided at equal intervals from each other, and each injects urea water in the direction C (second direction). Here, the direction B and the direction C are opposite directions, for example, the direction B is vertically downward, and the direction C is vertically upward.
In addition, the injection unit 30 includes a recovery port 35. The recovery port 35 is provided on the downstream side of the first injection port 31 and the second injection port 32, and recovers urea water flowing downstream by the flow of exhaust gas.

The plurality of first injection ports 31 constitute a first injection port group 33, and the plurality of second injection ports 32 constitute a second injection port group 34. As shown in FIG. 7, the first injection port group 33 and the second injection port group 34 are provided at positions facing each other in the exhaust pipe 150. That is, they are provided at the same position in the axial direction of the exhaust pipe 150. However, each of the first injection ports 31 included in the first injection port group 33 and each of the second injection ports 32 included in the second injection port group 34 are shifted from each other as shown in FIG. And provided at a position not facing each other. In other words, the jet jetted from the first jet port 31 and the jet jetted from the second jet port 32 are jetted in parallel to each other, but when viewed from the axial direction of the exhaust pipe 150, they are mutually in the horizontal direction. It is formed at a position shifted by a fixed amount. In this manner, jets in the direction B and jets in the direction C are alternately generated in the exhaust pipe 150.
With such an arrangement, the space occupied by the injection unit 30 in the exhaust pipe 150 is reduced as a whole, and the urea water jet simultaneously injected in the reverse direction from the first injection port 31 and the second injection port 32 It is possible not to cross each other, and urea can be mixed evenly in the whole exhaust gas.

  The jet of urea water is heated by the exhaust gas as it passes through the exhaust pipe 150, but immediately after being injected, the temperature is low and urea is relatively difficult to vaporize. That is, for example, when the first injection port 31 is provided downward on the inner wall on the upper side of the exhaust pipe 150, the exhaust gas passing through the periphery of the lower end of the inner wall of the jet flow from the first injection port 31 is relatively high-temperature urea. A relatively large amount of urea is mixed because it is in contact with water, but the amount of urea mixed is relatively small because the exhaust gas passing through the periphery of the upper end of the inner wall of the exhaust pipe 150 is in contact with a relatively low temperature urea water. . However, since the first injection port 31 and the second injection port 32 are provided in opposite directions, the amounts of urea vaporized from the urea water injected from each of them are complementary to each other, and as a result, the exhaust pipe The urea is not partially mixed in the cross section perpendicular to the 150 axis, and the urea can be uniformly mixed in the entire cross section perpendicular to the axis of the exhaust pipe 150. Therefore, the mixing of exhaust gas and urea can be promoted efficiently.

  In the above-described third embodiment, the first injection port 31 and the second injection port 32 inject urea water in the opposite directions, but this does not have to be the opposite direction, and the directions are different from each other. Any direction is possible as long as it realizes a state in which the water jets do not cross each other.

Embodiment 4 FIG.
In the fourth embodiment, an injection section is provided at a portion where the exhaust pipe is directed downward in the third embodiment.
FIG. 8 is a schematic cross-sectional view schematically showing a cross section along the axis of the exhaust pipe 160. The exhaust pipe 160 has a vertical portion 160a directed vertically downward in a part thereof, and the injection unit 40 is provided in the vertical portion 160a. It is assumed that the exhaust gas flows in the direction of arrow A.

The injection unit 40 includes a plurality of first injection ports 41 and a plurality of second injection ports 42. First injection port 41 and second injection port 42 have the same configuration as first injection port 31 and second injection port 32 of FIG. 6 in the third embodiment. However, as shown in FIG. 8, the first injection port 41 injects urea water in the direction D (first direction), and the second injection port 42 injects urea water in the direction E (second direction). . Here, the direction D and the direction E are both horizontal directions, but are opposite to each other.
The injection unit 40 includes a first recovery port 43 and a second recovery port 44. These are provided downstream of the first injection port 41 and the second injection port 42, that is, below the first injection port 41 with a predetermined distance ΔL. The first recovery port 43 corresponds to the first injection port 41 and recovers urea water injected from the first injection port 41. The second recovery port 44 corresponds to the second injection port 42 and recovers urea water injected from the second injection port 42. The predetermined distance ΔL can be appropriately designed according to the inner diameter of the exhaust pipe 150, the discharge pressure of the injection pump 112, the position, shape, size, and the like of the injection port and the recovery port.

  Even with such an arrangement, as in the third embodiment, the amounts of urea vaporized from the urea water injected from the first injection port 41 and the second injection port 42 are complementary to each other, resulting in exhaust gas. Urea can be mixed uniformly regardless of the position when the gas passes through the injection unit 40.

In the fourth embodiment described above, the first recovery port 43 and the second recovery port 44 are provided as the recovery ports. However, as a modification, only one recovery port may be provided.
FIG. 9 is a schematic cross-sectional view schematically showing a cross section according to such a modification. The exhaust pipe 170 has a vertical portion 170a directed vertically downward in a part thereof, and the injection unit 50 is provided in the vertical portion 170a. It is assumed that the exhaust gas flows in the direction of arrow A.

The injection unit 50 includes a plurality of first injection ports 51 and a plurality of second injection ports 52. The first injection port 51 injects urea water in the direction F (first direction), and the second injection port 52 injects urea water in the direction G (second direction).
The injection unit 40 includes a single recovery port 53. The recovery port 53 is provided on the downstream side of the first injection port 51 and the second injection port 52, that is, below, at the end of the vertical portion 170a. The urea water injected from the first injection port 51 and the second injection port 52 reaches the recovery port 53 directly or after colliding with the inner wall of the vertical portion 170a. As described above, the urea water sprayed in a plurality of directions can be efficiently recovered by the single recovery port 53.

Embodiment 5 FIG.
In the fifth embodiment, the direction of the jet of urea water is the four directions in the third embodiment.
FIG. 10 is a cross-sectional view illustrating the configuration of the injection unit 60 that causes urea water to flow through the exhaust pipe 150, and is a cross section perpendicular to the axis of the exhaust pipe 150. FIG. 11 is a schematic cross-sectional view schematically showing a cross section along the axis of the exhaust pipe 150. It is assumed that the exhaust gas flows in the direction of arrow A.

  The injection unit 60 includes a plurality of first injection ports 61, a plurality of second injection ports 62, a plurality of third injection ports 63, and a plurality of fourth injection ports 64 as injection ports for injecting urea water. The plurality of first injection ports 61 are provided at equal intervals from each other, and each injects urea water in the direction H (first direction). The plurality of second injection ports 62 are provided at equal intervals from each other, and each injects urea water in the direction I (second direction). Here, the direction H and the direction I are opposite directions, for example, the direction H is vertically downward, and the direction I is vertically upward.

The third injection port 63 and the fourth injection port 64 are provided downstream of the first injection port 61 and the second injection port 62 in the exhaust pipe 150. The plurality of third injection ports 63 are provided at equal intervals from each other, and each injects urea water in the direction J (third direction). The plurality of fourth injection ports 64 are provided at equal intervals from each other, and each injects urea water in the direction K (fourth direction). Here, the direction J and the direction K are directions opposite to each other. The direction J and the direction K are directions orthogonal to the direction H and the direction I.
In addition, the injection unit 60 includes a recovery port 69. The recovery port 69 is provided on the downstream side of the first injection port 61, the second injection port 62, the third injection port 63, and the fourth injection port 64, and recovers urea water flowing downstream by the flow of exhaust gas. To do.

The plurality of first injection ports 61 constitute the first injection port group 65 in the same manner as the plurality of first injection ports 31 of the third embodiment (FIG. 6). The plurality of second injection ports 62 constitute a second injection port group 66 in the same manner as the plurality of second injection ports 32 of the third embodiment (FIG. 6). That is, the first injection port group 65 and the second injection port group 66 are provided at positions that face each other, and each of the first injection ports 61 and each of the second injection ports 62 are provided at positions that do not face each other.
The plurality of third injection ports 63 constitute a third injection port group 67, and the plurality of fourth injection ports 64 constitute a fourth injection port group 68. The third injection port group 67 and the fourth injection port group 68 are provided at positions facing each other in the exhaust pipe 150. That is, they are provided at the same position in the axial direction of the exhaust pipe 150. However, each of the third injection ports 63 included in the third injection port group 67 and each of the fourth injection ports 64 included in the fourth injection port group 68 are shifted from each other as shown in FIG. And provided at positions that do not face each other.
In this way, in the exhaust pipe 150, jets in the direction H and jets in the direction I are alternately generated, and further, jets in the direction J and jets in the direction K are alternately generated downstream thereof. .

  Thus, the first injection port 61 and the second injection port 62 are provided in opposite directions, the third injection port 63 and the fourth injection port 64 are provided in opposite directions, and the first injection port. 61 and the 2nd injection port 62, and the 3rd injection port 63 and the 4th injection port 64 are provided in the direction which mutually orthogonally crosses. For this reason, the amounts of urea vaporized from the jets from the respective injection ports are complementary to each other, and as a result, the urea can be uniformly mixed regardless of the position when the exhaust gas passes through the injection unit 60. it can. Therefore, the mixing of exhaust gas and urea can be promoted efficiently.

In Embodiment 5 described above, the third injection port 63 and the fourth injection port 64 are provided on the downstream side of the first injection port 61 and the second injection port 62, but this may be reversed. That is, the third injection port 63 and the fourth injection port 64 may be provided on the upstream side of the first injection port 61 and the second injection port 62.
In the fifth embodiment, the first injection port 61 and the second injection port 62 inject urea water in opposite directions, and the third injection port 63 and the fourth injection port 64 are in opposite directions. The urea water is injected, but these directions do not have to be reversed, and any direction may be used as long as it realizes a state in which the jets of urea water do not intersect with each other.

Embodiment 6 FIG.
In the sixth embodiment, an injection section is provided at a portion where the exhaust pipe faces downward in the fifth embodiment.
FIG. 12 is a schematic cross-sectional view schematically showing a cross section along the axis of the exhaust pipe 160 in the exhaust pipe 160 similar to FIG. The injection unit 70 is provided in the vertical part 160 a of the exhaust pipe 160. It is assumed that the exhaust gas flows in the direction of arrow A.

The injection unit 70 includes a plurality of first injection ports 71, a plurality of second injection ports 72, a plurality of third injection ports 73, and a plurality of fourth injection ports (not shown). These injection ports have the same configuration as the corresponding injection ports in the fifth embodiment (FIG. 10). However, since the injection part 70 is provided in the vertical part 160a, the directions of the urea water injected by these injection ports are all horizontal.
The injection unit 70 corresponds to the first injection port 71, the second injection port 72, the third injection port 73, and the fourth injection port (not shown), and the first recovery port 75 and the second recovery port 76. , A third recovery port (not shown) and a fourth recovery port 78 are provided. These recovery ports are provided at a predetermined distance ΔL on the downstream side, that is, below the corresponding injection ports.

  Even with such an arrangement, as in the fifth embodiment, the amounts of urea vaporized from the urea water injected from the injection ports are complementary to each other, and as a result, when the exhaust gas passes through the injection unit 70, Urea can be mixed uniformly regardless of the position. Therefore, the mixing of exhaust gas and urea can be promoted efficiently.

In Embodiment 6 described above, four recovery ports corresponding to the four injection ports are provided, but as a modification, only one recovery port may be provided.
FIG. 13 is a schematic cross-sectional view schematically showing a cross section according to such a modification. The exhaust pipe 170 has a vertical portion 170a directed vertically downward in a part thereof, and the injection unit 80 is provided in the vertical portion 170a. It is assumed that the exhaust gas flows in the direction of arrow A.

  The injection unit 80 includes a plurality of first injection ports 81, a plurality of second injection ports 82, a plurality of third injection ports 83, and a plurality of fourth injection ports (not shown). The injection unit 80 includes a single recovery port 84. The recovery port 84 is provided on the downstream side of each injection port, that is, below, at the end of the vertical portion 170a. The urea water injected from each injection port reaches the recovery port 84 directly or after colliding with the inner wall of the vertical portion 170a. As described above, the urea water sprayed in a plurality of directions can be efficiently recovered by the single recovery port 84.

Embodiment 7 FIG.
In the seventh embodiment, the configuration of the recovery port 12 is variously modified in the first embodiment.
FIG. 14 shows the configuration of the recovery port 200 as an example of the configuration of the recovery port according to the seventh embodiment. The collection port 200 has a reflective surface 201 at a position of depth D1. The reflecting surface 201 directs urea water injected toward the recovery port 200 in the direction of the arrow R1 toward the internal space 150a of the exhaust pipe 150 (that is, toward the inside of the exhaust pipe 150), for example, in the direction of the arrow R2. Bounce back, thereby spreading the splash of urea water in the internal space 150a.
The reflective surface 201 may be any material that reflects urea water to such an extent that splashes diffuse, and can be realized by a metal surface or other structure. Moreover, you may use the surface in which the process for reflection was given.
By using such a recovery port 200, part of the urea water reaches the recovery port 200 and then rebounds by the reflecting surface 201 to be returned to the internal space 150a as a minute droplet. Therefore, it is possible to increase the minute droplets of urea water contained in the exhaust gas and efficiently promote the mixing of the exhaust gas and urea.

  In Embodiment 7 described above, the reflection surface 201 is provided at the recovery port 200, but may be provided at a location other than the recovery port 200 as long as it is a position that receives the jet of urea water in the exhaust pipe 150. That is, a part of the inner peripheral surface of the exhaust pipe 150 may constitute a reflecting surface.

FIG. 15 shows a configuration of the recovery port 210 as one modification of the configuration of the recovery port according to the seventh embodiment. The recovery port 210 includes a large depth recovery part 211 having a predetermined depth D2 from the internal space 150a as a non-reflective part. The depth D2 in FIG. 15 is larger than the depth D1 in FIG. 14 so that the urea water injected toward the recovery port 210 in the direction of the arrow R3 does not rebound, or at least does not rebound into the internal space 150a. The depth is large enough. In this case, the splashed urea water splash moves along a locus such as an arrow R4, and receives the suction force of the recovery pump 113 (FIG. 1) and enters the recovery side piping 114b and is recovered. This depth D2 can be appropriately designed depending on the material of the exhaust pipe 150, the state of the inner surface of the exhaust pipe 150, the discharge pressure of the injection pump 112, and the like.
By using the recovery port 210 having the non-reflective portion in this way, it is possible to prevent the splash of urea water from returning to the internal space 150a, so that an excessive amount of urea is prevented from being mixed with the exhaust gas, and the exhaust gas and urea are prevented. The mixing with can be accurately controlled.

FIG. 16 shows a configuration of the recovery port 220 as one of modifications of the configuration of the recovery port according to the seventh embodiment. The recovery port 220 includes a tapered surface 221 that guides the urea water so as not to rebound as a non-reflective portion. The tapered surface 221 is provided with an angle that does not repel urea water sprayed in the direction of the arrow R5 toward the recovery port 220, or at least does not rebound in the internal space 150a. In this case, the splashed urea water splash moves along a locus such as an arrow R6, and receives the suction force of the recovery pump 113 (FIG. 1) and enters the recovery side piping 114b and is recovered. The angle, shape, and other configurations of the tapered surface 221 can be appropriately designed according to the material of the exhaust pipe 150, the state of the inner surface of the exhaust pipe 150, the discharge pressure of the injection pump 112, and the like.
By using the recovery port 220 having the non-reflecting portion in this way, it is possible to prevent the splash of urea water from returning to the internal space 150a, so that an excessive amount of urea is prevented from being mixed with the exhaust gas, and the exhaust gas and urea are prevented. The mixing with can be accurately controlled.

FIG. 17 shows a configuration of the recovery port 230 as one of modifications of the configuration of the recovery port according to the seventh embodiment. The collection port 230 includes a shielding part 231 that shields the splash of urea water as a non-reflecting part. When the urea water sprayed in the direction of the arrow R7 toward the recovery port 230 is bounced back, the shielding portion 231 receives the urea water so that it does not return to the internal space 150a and guides it to the recovery side pipe 114b. For example, the urea water sprayed in the direction of the arrow R7 is bounced back along the arrow R8, collides with the shield 231 and is received and shielded, and the arrow R9 is caused by gravity or the suction force of the recovery pump 113 (FIG. 1). And enters the recovery side piping 114b and is recovered.
By using the recovery port 230 having the non-reflecting portion in this way, it is possible to prevent the splash of urea water from returning to the internal space 150a, so that an excessive amount of urea is prevented from being mixed with the exhaust gas, and the exhaust gas and urea are prevented. The mixing with can be accurately controlled.

The non-reflecting part according to the modification of the seventh embodiment described above can be called a recovery promoting part that reduces the reflection (bounce) of the injected urea water and promotes the recovery of the urea water.
Moreover, you may use combining the 2 or more non-reflective part which concerns on the modification of the above-mentioned Embodiment 7. FIG. For example, the taper surface 221 of FIG. 16 may be formed at a deep position like the large depth recovery part 211 of FIG. 15 and a shielding part of FIG.
Moreover, although Embodiment 7 changes variously the structure of the collection port 12 of Embodiment 1, the same deformation | transformation can be given also in Embodiment 2-6.

11 injection port (inlet), 12 recovery port, 13 jet (reducing agent),
21 inflow port, 22 recovery port, 23 urea water flow (reducing agent), 24 wire mesh (circulation guide member),
31 1st injection port, 32 2nd injection port, 33 1st injection port group, 34 2nd injection port group, 35 collection | recovery port,
41 1st injection port, 42 2nd injection port, 43 1st collection port (collection port), 44 1st collection port (collection port),
51 1st injection port, 52 2nd injection port, 53 collection | recovery port,
61 1st injection port, 62 2nd injection port, 63 3rd injection port, 64 4th injection port, 69 collection | recovery port,
71 1st injection port, 72 2nd injection port, 73 3rd injection port, 75 1st collection port (collection port), 76 2nd collection port (collection port), 78 4th collection port (collection port),
81 First injection port, 82 Second injection port, 83 Third injection port, 84 Recovery port,
100 purification device (exhaust gas purification device), 110 urea water circulation device, 112 injection pump (injection device), 120 internal combustion engine, 140 SCR catalyst (selective reduction catalyst), 150, 160, 170 exhaust pipe (exhaust path),
200 collection port, 201 reflective surface, 210 collection port, 211 deep collection unit (collection promotion unit), 220 collection port, 221 tapered surface (collection promotion unit), 230 collection port, 231 shielding unit (collection promotion unit).

Claims (15)

An exhaust gas purification device that purifies exhaust gas of an internal combustion engine using a reducing agent,
An inlet through which the reducing agent is circulated in an exhaust path through which the exhaust gas passes;
A recovery port for recovering the circulated reducing agent from the exhaust path;
An exhaust gas purification device comprising:   The exhaust gas purifying device according to claim 1, wherein both the inflow port and the recovery port are provided on a wall surface of the exhaust path. The recovery port is provided on the gravity direction side as viewed from the inflow port,
The exhaust gas purifying apparatus according to claim 1 or 2, wherein the reducing agent is supplied in a continuously continuous state from the inlet to the recovery port. The exhaust gas purification device according to any one of claims 1 to 3, wherein the inflow port is an injection port for injecting the reducing agent.   The exhaust gas purification device according to claim 4, wherein the injection port injects the reducing agent toward the recovery port. The injection port is
A first injection port for injecting the reducing agent in a first direction;
The exhaust gas purifying device according to claim 4 or 5, comprising a second injection port that injects the reducing agent in a second direction that is different from the first direction.   The exhaust gas purifying device according to claim 6, comprising a first injection port group including a plurality of the first injection ports and a second injection port group including the plurality of the second injection ports.   The exhaust gas purification device according to claim 7, wherein the first injection port and the second injection port inject the reducing agent in a direction facing each other. The injection port is
A third injection port for injecting the reducing agent in a third direction orthogonal to the first direction;
A fourth injection port for injecting the reducing agent in a fourth direction opposite to the third direction;
The said 3rd injection port and the said 4th injection port are provided in any one of Claims 6-8 provided in the downstream or the upstream of the said 1st injection port and the said 2nd injection port in the said exhaust path. Exhaust gas purification device. In the exhaust path, comprising a flow guide member provided across the inlet and the recovery port,
The exhaust gas purifying device according to any one of claims 1 to 3, wherein at least a part of the reducing agent flows along the flow guide member.   The exhaust gas purification device according to claim 10, wherein the flow guide member is a net.   The exhaust gas purification device according to any one of claims 4 to 9, wherein the exhaust path or the recovery port includes a reflective surface that repels the injected reducing agent into the exhaust path to diffuse the splashes. .   The exhaust gas purification device according to claim 5, wherein the recovery port includes a recovery promoting unit that promotes recovery of the injected reducing agent. The collection promoting unit
A large depth recovery section in which the depth of the recovery port from the exhaust path is increased;
A tapered surface for guiding the reducing agent;
The exhaust gas purifying device according to claim 13, comprising at least one shielding portion that shields the spray of the reducing agent. The reducing agent is urea water;
The exhaust gas purification device includes a selective reduction catalyst,
The inlet is provided on the upstream side of the selective reduction catalyst in the exhaust path,
The exhaust gas purification device according to any one of claims 1 to 14, wherein the selective reduction catalyst promotes a reduction reaction by urea or ammonia generated from the urea water and nitrogen oxides in the exhaust gas. .

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