US20120144812A1

US20120144812A1 - Dosing module for exhaust post treatment system of vehicle

Info

Publication number: US20120144812A1
Application number: US13/174,075
Authority: US
Inventors: Gisoo Hyun
Original assignee: Hyundai Motor Co; Kia Motors Corp
Current assignee: Hyundai Motor Co; Kia Corp
Priority date: 2010-12-09
Filing date: 2011-06-30
Publication date: 2012-06-14
Also published as: DE102011051875A1; JP5779410B2; KR20120064345A; DE102011051875A8; DE102011051875B4; JP2012122469A; KR101251518B1

Abstract

A dosing module for an exhaust gas post treatment system of a vehicle, which may be used to inject a reducing agent along a flow direction of exhaust gas at a front side of a selective catalyst reduction (SCR) unit, may include a dosing main body having a connection portion that may be connected to the SCR unit and an inflow portion into which the exhaust gas flows, an injector that may be disposed at a boss portion that may be mounted on the dosing main body to inject the reducing agent into the dosing main body, and a guide member that may be disposed inside the dosing main body to guide the exhaust gas flowing into the dosing main body along a predetermined route.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2010-0125531 filed in the Korean Intellectual Property Office on Dec. 9, 2010, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
An exemplary embodiment of the present invention relates to an exhaust system of a vehicle. More particularly, the present invention relates to a dosing module of a selective catalyst reduction (SCR) unit for exhaust gas post treatment.
2. Description of Related Art
Generally, an exhaust system of an engine is provided with exhaust gas post treatment such as with a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a selective catalyst reduction (SCR) unit, etc., so as to reduce diesel particulate matter (PM) and nitrogen oxide (NO_x).
Of these, a reducing agent (for example, a urea solution) is injected into the exhaust gas by an injector, the reducing agent (urea) is hydrolyzed to ammonia (NH₃) by the heat of the exhaust gas, and nitrogen oxide (NO_x) of the exhaust gas reacts with the ammonia (NH₃) through a catalyst of the SCR unit to be transformed into nitrogen (N₂) gas and water (H₂O).
In the conventional exhaust gas post treatment device such as one using the DOC, the DPF, and the SCR unit, as an example, the DOC and the DPF are disposed in a flowing direction of the exhaust gas, and the SCR unit is disposed at a downstream side of the DPF. Further, a dosing module having an injector is disposed between the DPF and the SCR unit to inject the reducing agent.
In a conventional dosing module, the injection speed of the reducing agent is increased by raising the injection pressure according to EM (emission) standards.
However, the spray depth of the reducing agent from the injector is increased in the conventional art such that the injected reducing agent is accumulated on the interior wall of the exhaust gas line, i.e., there is a problem that a wall wetting phenomenon is generated.
That is, the wall wetting phenomenon of the reducing agent that is injected is a cause of deterioration of purification efficiency of nitrogen oxide and activation of the SCR, and in a case that the liquid element of the reducing agent evaporates on the interior wall of the exhaust gas line, a solid residue thereof remains, and resultantly it becomes difficult to control the injection amount.
Meanwhile, in another conventional art, a mixer is disposed in the exhaust gas line so as to mix the reducing agent that is injected by the injector with the exhaust gas and so as to prevent the wall wetting.
However, since the mixer is disposed in the exhaust gas line, material cost is increased thereby and there is a problem that the durability thereof is reduced.
On the other hand, in another conventional art, the injector is disposed at a curved pipe portion of the exhaust gas line so as to prevent the wall wetting phenomenon such that the reducing agent is injected into the exhaust gas passing the curved pipe portion.
However, since the injector is disposed at the curved portion of the exhaust gas line, it is necessary to secure appropriate positioning such that the reducing agent may be hydrolyzed to ammonia (NH₃) by the heat of the exhaust gas. Accordingly, it is necessary to secure the shape of the exhaust pipe to provide the appropriate positioning, the entire post treatment layout becomes complicated thereby, and there is a problem that it is difficult to dispose the injector on the layout.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a dosing module for an exhaust gas post treatment system of a vehicle having advantages of substantially preventing a wall wetting phenomenon of a reducing agent and improving efficiency of a selective catalyst reduction (SCR) unit without injecting the reducing agent into a curved pipe and without disposing a mixer in the exhaust pipe.
A dosing module for an exhaust gas post treatment system of a vehicle, which may be used to inject a reducing agent along a flow direction of exhaust gas at a front side of a selective catalyst reduction (SCR) unit, may include a dosing main body having a connection portion that may be connected to the SCR unit and an inflow portion into which the exhaust gas flows, an injector that may be disposed at a boss portion that may be mounted on the dosing main body to inject the reducing agent into the dosing main body, and a guide member that may be disposed inside the dosing main body to guide the exhaust gas flowing into the dosing main body along a predetermined route.
The guide member may have a plate shape to separate the connection portion from the inflow portion in the dosing main body.
One end of the guide member may be fixed to an inside wall of the dosing main body and the other end thereof may be bent from the inside wall to may have a curved shape, wherein the curved shape may be bent toward the injector with a predetermined curvature to enclose the inflow portion therein.
The guide member may have a plurality of holes, wherein a baffle member may be mounted in the dosing main body to be engaged with the guide member and an inside wall of the dosing main body to form the inflow portion.
The baffle member may have a plate shape except at the inflow portion in the dosing main body, wherein the baffle member forms a flow passage between the guide member and an inside wall of the dosing main body.
The baffle member may be disposed on a slant toward the inflow portion in the dosing main body.
The injector may be disposed on a slant along the flow direction of the exhaust gas on the boss member, wherein the injector injects the reducing agent toward the curved portion of the guide member.
The connecting portion forms a connecting passage that may be connected to the SCR unit at a lower portion of the dosing main body.
The dosing module for an exhaust gas post treatment system of a vehicle prevents the wall wetting phenomenon in an exemplary embodiment of the present invention without injecting the reducing agent to the curved pipe and without disposing the mixer in the exhaust pipe, and the mixture of the exhaust gas and the reducing agent and the uniformity and the reaction activity thereof are improve regardless of the layout of the vehicle such that the efficiency of the SCR unit is increased.
The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing an exhaust gas post treatment system of a vehicle according to an exemplary embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a dosing module for an exhaust gas post treatment system of a vehicle according to an exemplary embodiment of the present invention.

FIG. 3 is a schematic diagram of an assembled front view of FIG. 2.

FIG. 4A and FIG. 4B show operational states of a dosing module for an exhaust gas post treatment system of a vehicle according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.
In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.
Portions having no relation with the description will be omitted in order to explicitly explain an exemplary embodiment of the present invention, and the same reference numerals will be used for the same or similar elements throughout the specification.
In the drawings, size and thickness of each element is approximately shown for better understanding and ease of description. Therefore, the present invention is not limited to the drawings, and the thicknesses of layers, films, panels, regions, etc., are exaggerated for clarity.
FIG. 1 is a schematic block diagram showing an exhaust gas post treatment system of a vehicle according to an exemplary embodiment of the present invention.
Referring to the drawings, an exemplary embodiment of the present invention can be applied to an exhaust gas post treatment system 200 that purifies exhaust gas generated from a diesel engine for a commercial vehicle.
Here, the exhaust gas post treatment system 200, for example, includes a diesel oxidation catalyst (DOC) 1 that is disposed on the exhaust line, a diesel particulate filter (DPF) 3 that is disposed at a downstream side of the DOC 1, and a selective catalyst reduction (SCR) unit 5 that is disposed at a downstream side of the DPF 3.
In this case, the DOC 1 oxidizes all hydrocarbons and carbon monoxide of the exhaust gas and oxidizes nitrogen monoxide to nitrogen dioxide.
The DPF 3 includes a catalyst support for trapping particulate matter (PM) included in the exhaust gas, and the catalyst support eliminates the PM through a chemical reaction.
Further, the SCR unit 5 chemically reduces nitrogen oxide passing the DOC 1 and the DPF 3 to N₂gas by using a reducing agent such as a urea solution.
That is, the reducing agent is transformed to ammonia by the oxidation heat, and the nitrogen oxide reacts with the ammonia through the catalyst of the SCR 5 to be transformed into N₂gas and water.
Meanwhile, the exhaust gas post treatment system 200 includes a dosing module 100 that is disposed between the DPF 3 and the SCR 5 according to the present exemplary embodiment, which is used to inject the reducing agent along a flowing direction of the exhaust gas.
The dosing module 100 according to the present exemplary embodiment is not limited by a layout of a vehicle, and it enhances mixing of the exhaust gas and the reducing agent and improves efficiency of the SCR unit 5 by reaction activation and improved uniformity.
FIG. 2 is an exploded perspective view showing a dosing module for an exhaust gas post treatment system of a vehicle according to an exemplary embodiment of the present invention, and FIG. 3 is a schematic diagram of an assembled front view of FIG. 2.
Referring to the drawing, according to an exemplary embodiment of the present invention, the dosing module 100 for an exhaust gas post treatment system of a vehicle basically includes a dosing main body 10, an injector 30, a guide member 50, and a baffle member 70, and these are described as follows.
As shown in FIG. 1, the dosing main body 10 can connects the DPF 3 and the SCR unit 5 of the exhaust gas post treatment system 200 in the present exemplary embodiment.
One side of the dosing main body 10 is closed and the other side thereof is opened to have a cylinder shape, and the dosing main body 10 has an inflow portion 11 into which the exhaust gas flows and a connecting portion 13 that is connected to the SCR unit 5.
The inflow portion 11 is an inlet into which the exhaust gas flows, and can be formed in another side of the dosing main body 10 through the guide member 50 that is to be described hereafter and the baffle member 70.
The combination structure of the guide member 50 that forms the inflow portion 11 and the baffle member 70 will be described hereafter.
The connecting portion 13 is connected to the SCR unit 5 through a pipe to form a connecting passage 12 that is connected to the SCR unit 5.
Here, the connecting passage 12 has a narrower cross-section than that of the dosing main body 10, and can be formed at a lower side of the dosing main body 10.
The injector 30 that is to be described hereafter is disposed at a boss member of an upper side of the dosing main body 10.
An opening is formed to be connected to an interior space of the dosing main body 10, and the boss member 15 is disposed around the opening to be welded on the exterior circumference of the dosing main body 10.
In this case, the boss member 15 is biased from the upper center of the exterior circumference of the dosing main body 10 in one direction by a predetermined distance, and a mounting bracket 17 for mounting the injector 30 is disposed on the boss member 15.
In the above, the injector 30 is used to inject the reducing agent into the dosing main body 10, and is mounted on the opening of the boss member 15 through the mounting bracket 17. The injector 30 is mounted at the boss member on a slant along the flowing direction of the exhaust gas.
The injector 30 is a secondary injection device of a conventional art that is used in an exhaust system of this field, and a detailed description thereof will be omitted in this specification.
The guide member 50 guides the exhaust gas flowing into the dosing main body 10 through the inflow portion 11 along a predetermined line in the present exemplary embodiment.
Also, the guide member 50 promotes mixing of the reducing agent injected by the injector 30 with the exhaust gas and atomizing of the reducing agent to improve mixture uniformity of the exhaust gas and the reducing agent.
The guide member 50 is disposed inside the dosing main body 10 to have a plate shape that separates the inflow portion 11 from the connecting portion 13 in the dosing main body 10.
Here, the guide member 50 is welded on the interior wall of the dosing main body 10, wherein one end thereof is fixed on the interior wall corresponding to the inflow portion 11 and the other end thereof is extended from the fixed portion.
In this case, the other end portion of the guide member 50 is bent to have a semi-circular shape, and one end portion thereof has a softly curved shape to be fixed on the interior wall of the dosing main body 10.
A round portion 51 of the other end portion of the guide member 50 generates a strong turning flow in the exhaust gas flowing into the dosing main body 10 to improve the mixture uniformity of the exhaust gas and the reducing agent.
A plurality of holes 53 are formed on all areas of the guide member 50 and the holes 53 promotes mixing of the exhaust gas and the reducing agent, wherein the reducing agent is injected by the injector 30 and the exhaust gas is guided by the guide member 50.
Meanwhile, the injector 30 is biased toward one side direction from the upper center of the dosing main body 10 by the boss member 15 that is described above such that the injector 30 injects the reducing agent toward the round portion 51 of the guide member 50.
That is, since the reducing agent of the injector 30 is injected toward the round portion 51 of the guide member 50 in which the holes 53 are formed, the reducing agent does not collide with the interior wall of the dosing main body 10 at an early injection stage.
The baffle member 70 forms the inflow portion 11 into which the exhaust gas flows, induces the exhaust gas to the inflow portion 11, and improves the straightness of the reducing agent by preventing axial movement of the exhaust gas in the present exemplary embodiment.
The baffle member 70 is fixed on the interior wall and the guide member 50 to have a plate shape covering a part except the inflow portion 11 in the dosing main body 10.
That is, the baffle member 70 contacts the guide member 50 to be fixed on the interior wall of the dosing main body 10, and the inflow portion 11 corresponding to the shape of the guide member 50 is formed.
The baffle member 70 covers between the guide member 50 and the dosing main body 10 except at the inflow portion 11 to form a flow passage 71 of the exhaust gas, and an inlet of the exhaust gas is formed by the inner side of the guide member 50 and the interior wall of the dosing main body 10.
Here, it is desirable for the baffle member 70 to be slanted toward the inflow portion 11 on the interior surface of the dosing main body 10 so as to induce the exhaust gas toward the inflow portion 11.
Accordingly, in a dosing module 100 for an exhaust gas post treatment system of a vehicle according to an exemplary embodiment of the present invention, the exhaust gas that has passed the DOC 1 and the DPF 3 is induced to the inflow portion 11 by the baffle member 70 of the dosing main body 10 to flow through the inflow portion 11.
Referring to FIG. 4A and FIG. 4B, operation of the dosing module 100 will be described hereafter according to the present exemplary embodiment. The exhaust gas collides with the round portion 51 of the guide member 50 to form a strong turning flow and flows through the flow passage 71 between the guide member 50 and the dosing main body 10.
In this process, the injector 30 injects the reducing agent and is disposed on the slant toward one side direction from the upper center of the dosing main body 10 such that the reducing agent is injected toward the round portion 51 of the member 50.
The baffle member 70 prevents axial direction flowing of the exhaust gas to improve the straightness of the reducing agent that is injected from the injector 30.
Because the reducing agent that is injected from the injector 30 is injected toward the round portion 51 of the guide member 50 where the holes 53 are formed in the present exemplary embodiment, the reducing agent is prevented from being attached to the interior wall of the dosing main body 10 at an early stage thereof.
Meanwhile, the reducing agent injected by the injector 30 collides with the guide member 50 of a high temperature in the present exemplary embodiment and the atomization thereof is improved thereby, and the mixing time of the exhaust gas and the reducing agent is secured.
The reducing agent collides with the exhaust gas flowing through the holes 53 of the guide member 50 to be mixed therewith and the atomization thereof is promoted. The reducing agent is uniformly mixed by the strong turning flow of the exhaust gas that is formed by the flow passage 71.
Accordingly, the reducing agent is transformed to ammonia (NH₃) by the heat of the exhaust gas in the dosing main body 10 in the present exemplary embodiment, and the NH₃flows into the SCR unit (5 of FIG. 1) through the connecting portion 13 to react with nitrogen oxide in all areas of the SCR 5 by an venturi effect.
As described, a dosing module 100 for an exhaust gas post treatment system of a vehicle prevents the wall wetting phenomenon in an exemplary embodiment of the present invention without injecting the reducing agent into a curved pipe and without disposing the mixer in the exhaust pipe.
With this, the mixture of the exhaust gas and the reducing agent and the uniformity and the reaction activity thereof are improved regardless of the layout of the vehicle in the present exemplary embodiment such that the efficiency of the SCR unit 5 is increased.
For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.

Claims

1. A dosing module for an exhaust gas post treatment system of a vehicle, which is used to inject a reducing agent along a flow direction of exhaust gas at a front side of a selective catalyst reduction (SCR) unit, comprising:

a dosing main body having a connection portion that is connected to the SCR unit and an inflow portion into which the exhaust gas flows;

an injector that is disposed at a boss portion that is mounted on the dosing main body to inject the reducing agent into the dosing main body; and

a guide member that is disposed inside the dosing main body to guide the exhaust gas flowing into the dosing main body along a predetermined route.

2. The dosing module for the exhaust gas post treatment system of claim 1, wherein the guide member has a plate shape to separate the connection portion from the inflow portion in the dosing main body.

3. The dosing module for the exhaust gas post treatment system of claim 2, wherein one end of the guide member is fixed to an inside wall of the dosing main body and the other end thereof is bent from the inside wall to have a curved shape.

4. The dosing module for the exhaust gas post treatment system of claim 3, wherein the curved shape is bent toward the injector with a predetermined curvature to enclose the inflow portion therein.

5. The dosing module for the exhaust gas post treatment system of claim 1, wherein the guide member has a plurality of holes.

6. The dosing module for the exhaust gas post treatment system of claim 5, wherein a baffle member is mounted in the dosing main body to be engaged with the guide member and an inside wall of the dosing main body to form the inflow portion.

7. The dosing module for the exhaust gas post treatment system of claim 6, wherein the baffle member has a plate shape except at the inflow portion in the dosing main body.

8. The dosing module for the exhaust gas post treatment system of claim 7, wherein the baffle member forms a flow passage between the guide member and an inside wall of the dosing main body.

9. The dosing module for the exhaust gas post treatment system of claim 7, wherein the baffle member is disposed on a slant toward the inflow portion in the dosing main body.

10. The dosing module for the exhaust gas post treatment system of claim 3, wherein the injector is disposed on a slant along the flow direction of the exhaust gas on the boss member.

11. The dosing module for the exhaust gas post treatment system of claim 10, wherein the injector injects the reducing agent toward the curved portion of the guide member.

12. The dosing module for the exhaust gas post treatment system of claim 1, wherein the connecting portion forms a connecting passage that is connected to the SCR unit at a lower portion of the dosing main body.