US20120285144A1

US20120285144A1 - Exhaust after treatment system and method for treating exhaust

Info

Publication number: US20120285144A1
Application number: US13/107,367
Authority: US
Inventors: Naser I. Hineiti; Steven M. Yocum
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2011-05-13
Filing date: 2011-05-13
Publication date: 2012-11-15
Also published as: DE102012207827A1; CN102777239A

Abstract

In one exemplary embodiment of the invention an exhaust after treatment system is provided that includes an inlet housing, an inlet in the inlet housing configured to receive an exhaust gas flow from an internal combustion engine and an outlet in the inlet housing configured to direct the exhaust gas flow to a pollutant reduction device. The system also includes a deflector coupled to an inner surface of the inlet housing, the deflector configured to receive the exhaust gas flow from the inlet and uniformly direct the exhaust flow through the outlet and to the pollutant reduction device.

Description

FIELD OF THE INVENTION

Exemplary embodiments of the invention are related to internal combustion engines, and more particularly, to exhaust after treatment systems of internal combustion engines.

BACKGROUND

Manufacturers of internal combustion engines, particularly diesel engines, are presented with the challenging task of complying with current and future emission standards for the release of nitrogen oxides, particularly nitrogen monoxide, as well as unburned and partially oxidized hydrocarbons, carbon monoxide, particulate matter, and other pollutants. In order to reduce the pollutant emissions of an internal combustion engine, an exhaust gas after treatment system is used to reduce pollutants within the exhaust gas flowing from the engine.
Exhaust gas after treatment systems typically include one or more after treatment devices, such as oxidation catalysts, catalytic converters, mixer elements and urea injectors. Variations in exhaust gas flow, such as lack of uniform flow, can adversely affect the performance of the after treatment system, thus causing unwanted pollutants to be released from the system. As emissions standards become increasingly stringent, improving the uniformity and distribution of the exhaust flow as it enters and flows through the after treatment system is desirable in meeting those standards

SUMMARY OF THE INVENTION

In one exemplary embodiment of the invention an exhaust after treatment system is provided that includes an inlet housing, an inlet in the inlet housing configured to receive an exhaust gas flow from an internal combustion engine and an outlet in the inlet housing configured to direct the exhaust gas flow to a pollutant reduction device. The system also includes a deflector coupled to an inner surface of the inlet housing, the deflector configured to receive the exhaust gas flow from the inlet and uniformly direct the exhaust flow through the outlet and to the pollutant reduction device.
In another exemplary embodiment of the invention a method for treating exhaust from an internal combustion engine is provide, the method including the steps of receiving an exhaust gas flow from the internal combustion engine via an inlet in a housing and directing the exhaust gas flow to form a uniform exhaust gas flow to an outlet of the housing. The method further includes directing the uniform exhaust flow to a pollutant reduction device.
The above features and advantages and other features and advantages of the invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which:

FIG. 1 is a schematic diagram of an embodiment of an engine system;

FIG. 2 is a detailed sectional view of an embodiment of an exhaust after treatment system;

FIG. 3 is a detailed sectional end view of an exemplary inlet housing; and

FIG. 4 is a sectional side view of the inlet housing shown in FIG. 3.

DESCRIPTION OF THE EMBODIMENTS

The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
FIG. 1 is a schematic diagram of an embodiment of an engine system 100. The engine system 100 includes an internal combustion engine 102, an exhaust system 104 and an engine controller 106. The exhaust system 104 includes an exhaust manifold 108, an exhaust after treatment apparatus 110 and an exhaust conduit 112. Cylinders 116 are located in internal combustion engine 102, wherein the cylinders receive a combination of combustion air and fuel. The combustion air/fuel mixture is combusted resulting in reciprocation of pistons (not shown) located in the cylinders 116. The reciprocation of the pistons rotates a crankshaft (not shown) to deliver motive power to a vehicle powertrain (not shown) or to a generator or other stationary recipient of such power (not shown) in the case of a stationary application of the internal combustion engine 102. The combustion of the air/fuel mixture causes a flow of exhaust gas 118 through the exhaust manifold 108 and into the exhaust gas after treatment apparatus 110, wherein the exhaust after treatment apparatus 110 includes an inlet housing 119, a first catalyst treatment device such as oxidation catalyst 120, a mixer element 122 and a second catalytic treatment device 124. The exhaust after treatment apparatus 110 reduces, oxidizes, traps or otherwise treats various regulated constituents of the exhaust gas 118 prior to its release to the atmosphere, as shown by a reduced pollutant flow of exhaust gas 126.
In addition, the exhaust after treatment apparatus 110 and a fluid supply 125 are operationally coupled to and controlled by engine controller 106. The engine controller 106 collects information regarding the operation of the internal combustion engine 102 from sensors 128 a-128 n, such as temperature (intake system, exhaust system, engine coolant, ambient, etc.), pressure, exhaust flow rates, NOx concentrations and, as a result, may adjust the amount of a fluid, such as urea, injected into mixer element 122. As used herein the term controller refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. In an exemplary embodiment, the inlet housing 119 the diesel exhaust gas flow 118 and directs it into the oxidation catalyst 120 to remove pollutants and conform with emissions regulations. The inlet housing 119 improves the uniformity and distribution of the exhaust gas flow 118 as it flows into the oxidation catalyst to enhance performance of the after treatment system 110.
In accordance with an exemplary embodiment of the invention, FIG. 2 illustrates a detailed sectional view of the exhaust after treatment system 110. The after treatment system 110 includes the inlet housing 119 and a rigid canister 204. The after treatment system 110 receives the exhaust gas 118 from the internal combustion engine 102, which may include a forced induction system (e.g., turbocharger) in some embodiments. An exhaust gas flow 126 depicts flow from the rigid canister 204 after the pollutants have been removed. The inlet housing 119 includes an inlet 210, deflectors 212 and an outlet 214. The inlet housing creates a uniform flow of exhaust gas 118 to flow into the rigid canister 204.
In an embodiment, the exhaust after treatment system 110 includes the oxidation catalyst 120, the mixer element 122 and the second catalytic treatment 124 device supported in the rigid canister 204. The exemplary components are configured to remove pollutants from the exhaust gas 118. Uniform flow of the exhaust gas 118 from the inlet housing 119 improves performance of the various catalytic components (122, 124) of exhaust after treatment system 110. For example, the deflectors 212 cause an improved flow uniformity of the exhaust gas as it flows from the outlet 214 to an inlet face 218 of the oxidation catalyst 120. The uniform flow of exhaust gas across the face 218 and thru the oxidation catalyst 120 provides improved flow through the component and more efficient use of the catalyst compound(s) disposed in the pollutant reduction 110 device. Further, by evenly distributing exhaust gas flow across the inlet face 218, substantially the entire body of the diesel oxidation catalyst 120 is used, thereby improving pollutant reduction and flow therethrough and enabling the internal combustion engine 102 to satisfy emission regulations.
FIG. 3 is a detailed sectional end view of the exemplary inlet housing 119. The inlet housing 119 may be of any suitable configuration and geometry to improve uniformity of exhaust gas flow, such as the illustrated elliptical shape. The deflectors 212 are curved deflectors oriented in relation to the inlet 210 and the incoming flow of the exhaust gas 118. As depicted, the deflectors extend substantially perpendicularly from an inner surface 299 of wall 300 of the inlet housing 119. In embodiments, the inlet housing includes one or more deflectors 212 extending from the wall 300. In addition, a side wall 302 extends substantially perpendicularly from the wall 300 as well, forming an outer wall of the inlet housing 119. In the depicted embodiment, a deflector 304 extends from the inner surface 301 of side wall 302 to further control flow within the inlet housing 119. The deflectors 212 and 304 may be any suitable shape and orientation to control flow, such as curved or straight members that are aligned with respect to the exhaust gas 118 inflow and/or flow into the rigid canister 204 and oxidation catalyst 120. The deflectors 212 and 304 may also be aligned or misaligned, and/or similar or different geometries and/or sizes depending on desired flow characteristics. The inlet housing 119 is formed by any suitable method, such as stamping or casting. The deflectors 212 and 304 are formed by a suitable method, such as by stamping with the inlet housing 119 or welding/brazing the deflectors 212 and 304 to the wall 300. The inlet housing 119 comprises a suitable durable material able to withstand high temperatures, such as any metal alloy (e.g., steel alloys or stainless steel).
FIG. 4 is a sectional side view of the inlet housing 119. As depicted, the exhaust gas 118 flows into the inlet 210 and is controlled and redirected by the deflectors 212. The deflectors 212 are arranged to cause a uniform exhaust gas flow 400 through the outlet 214 into the substrate of the oxidation catalyst 120 supported within rigid canister 204. In an embodiment, the deflectors 212 are coupled to the surface via couplings 402, which may be any suitable coupling. For example, the couplings 402 may include a braze, weld or other adhesive to attach the deflectors 212 to the wall 300. As shown in FIGS. 1-4, exemplary embodiments of the inlet housing 119 provide improved uniformity of exhaust flow 118 into the exhaust after treatment system 110. The improved flow uniformity improves performance of the after treatment system 110. In one embodiment, the improved uniformity of exhaust gas flow 400 at the outlet 214 of the inlet housing 119 is characterized by a flow uniformity index of about 0.80 to about 0.90. In other embodiments, the flow uniformity index is great than about 0.90. Flow uniformity index is widely used in the automotive industry to interpret the degree of flow distribution in the front of a substrate and in an embodiment is defined as the following:
$γ = 1.0 - \int_{A_{O}} Φ \partial A / (2 U_{avg} A_{O}); where$ $Φ = \langle \langle U \rangle - U_{avg} \rangle and U_{avg} = \int U \partial A / A_{O}$
Other values are as follows: U=instantaneous velocity at the face of a local area; U_avg=average velocity over the face where the flow uniformity index is being investigated; Φ=absolute difference between the instantaneous and the average velocity (always a positive value); and A₀=the total area over which the flow uniformity index is being investigated. According to the above definition, uniformity can be as high as 1.0 indicating a perfectly distributed flow. Higher uniformity index (closed to 1.0 is generally an indication of a better uniformly distributed flow).
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application.

Claims

1. An exhaust gas after treatment system comprising:

an inlet housing;

an inlet in the inlet housing configured to receive an exhaust gas flow from an internal combustion engine;

an outlet in the inlet housing configured to direct the exhaust gas flow to a pollutant reduction device disposed in the exhaust gas after treatment system; and

a deflector coupled to an inner surface of the inlet housing, the deflector configured to receive the exhaust gas flow from the inlet and uniformly direct the exhaust gas flow through the outlet and to the pollutant reduction device.

2. The system of claim 1, comprising a plurality of deflectors extending substantially perpendicularly from the inner surface.

3. The system of claim 2, comprising wherein the plurality of deflectors comprise curved members.

4. The system of claim 1, comprising a side deflector extending from a side wall of the elliptical shaped housing.

5. The system of claim 1, wherein the housing comprises an elliptical shape housing.

6. The system of claim 1, wherein a first exhaust gas flow direction through the inlet is substantially perpendicular to a second exhaust gas flow direction through the outlet.

7. The system of claim 1, wherein the deflector is configured to uniformly direct the exhaust gas flow through the outlet with a uniformity index greater than about 0.85.

8. The system of claim 1, wherein the pollutant reduction device comprises an oxidation catalyst.

9. The system of claim 1, wherein the inlet is configured to receive an exhaust gas flow from a turbocharger of the internal combustion engine.

10. The system of claim 1, wherein the elliptical shaped housing is formed by stamping.

11. The system of claim 1, wherein the deflector is coupled to the inner surface by a brazing or welding process.

12. A method for treating exhaust gas from an internal combustion engine, the method comprising:

receiving an exhaust gas flow from the internal combustion engine via an inlet in a housing;

directing the exhaust gas flow to form a uniform exhaust flow to an outlet of the housing; and

directing the uniform exhaust flow to a pollutant reduction device.

13. The method of claim 12, wherein directing the exhaust gas flow comprises deflecting the exhaust gas flow via a plurality of deflectors extending perpendicular from an inner surface of the housing.

14. The method of claim 13, wherein directing the exhaust gas flow comprises deflecting the exhaust gas flow via a side deflector extending from a side wall of the housing.

15. The method of claim 13, wherein directing the exhaust gas flow comprises deflecting the exhaust gas flow via the plurality of deflectors comprising a plurality of curved members.

16. The method of claim 12, wherein the housing comprises an elliptical shape housing.

17. The method of claim 12, wherein receiving the exhaust gas flow comprises receiving the exhaust gas flow in a first flow direction through the inlet that is substantially perpendicular to a second gas flow direction through the outlet.

18. The method of claim 12, wherein deflecting the exhaust gas flow comprises directing the uniform exhaust gas flow through the outlet with a uniformity index greater than about 0.85.

19. The method of claim 12, wherein directing the uniform exhaust gas flow comprises directing the uniform exhaust flow to an oxidation catalyst.

20. The method of claim 12, wherein receiving the exhaust gas flow comprises receiving the exhaust gas flow from a turbocharger of the internal combustion engine.