Patent Grant
8464516
The present disclosure relates to an exhaust gas treatment system. More particularly, an inlet for an exhaust treatment device is configured to improve exhaust flow and reduce back pressure.
Reductions in the nitrogen oxides (NOx) and particulate matter (PM) emitted from internal combustion engines continue to be of importance. In particular, increasingly stringent regulations relating to automotive diesel compression engines continue to be promulgated. While diesel particulate filters (DPF) are capable of achieving the required reductions in PM, there is a continuing need for improved systems that can provide the required reductions in NOx, in connection with the PM reduction provided by a DPF.
Systems have been proposed to provide a diesel oxidation catalyst (DOC) upstream from a DPF in order to provide an increased level of NO2 in the exhaust which reacts with the soot gathered in the DPF to produce a desired regeneration of the DPF. This method may be referred to as passive regeneration. Such systems, however, may have limited effectiveness at temperatures below 300° C. and typically produce a pressure drop across the oxidation catalyst that must be accounted for in the design of the rest of the system. Hydrogen or a hydrocarbon fuel may be delivered upstream of the DOC to generate temperatures greater than 600° F. and actively regenerate the DPF.
Some systems may include a burner to increase the temperature of the engine exhaust by igniting fuel and creating a flame that heats the exhaust to an elevated temperature that will allow for oxidation of particulate matter in a diesel particulate filter. Examples of such proposals are shown in commonly assigned and co-pending U.S. patent application Ser. No. 12/430,194, filed Apr. 27, 2009, entitled “Diesel Aftertreatment System” by Adam J. Kotrba et al., the entire disclosure of which is incorporated herein by reference.
While current burners for such systems may by suitable for their intended purpose, improvements may be desirable. For example, it may be advantageous to provide a burner having an exhaust gas inlet extending parallel to an exhaust gas outlet to reduce back pressure and alleviate component packaging and mounting concerns.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
An exhaust gas treatment device for treating an exhaust flow from an engine includes an inlet housing having an inlet opening for receipt of the exhaust flow from the engine aligned along a first axis. A main housing includes a cylindrical body portion defining a treatment zone and an exhaust outlet aligned along a second axis extending parallel to the first axis. The inlet housing is in fluid communication with and fixed to an outer surface of the main housing. The inlet housing includes a contoured wall including an end portion positioned opposite the inlet opening, an aperture extending through the wall transverse to the first axis, divergent side wall portions on opposite sides of the inlet opening, and a necked portion having a reduced cross-section positioned downstream of the inlet opening and upstream of the aperture. A component is coupled to the main housing for treating exhaust flowing through the treatment zone.
Furthermore, an exhaust gas treatment device for treating an exhaust flow from an engine includes an inlet housing having an inlet opening for receipt of the exhaust flow from the engine with the inlet opening being aligned along a first axis. A main housing includes a cylindrical body portion defining a treatment zone and an exhaust outlet aligned along a second axis extending parallel to the first axis. The inlet housing is in fluid communication with and fixed to an outer surface of the main housing. The inlet housing includes a contoured wall including an end portion positioned opposite the inlet opening and an aperture extending through the wall transverse to the first axis. A portion of the contoured wall opposite the aperture includes a radially outwardly sloping portion intersecting a radially inwardly sloping portion at an inflection point. The inflection point is positioned axially downstream from the inlet opening and upstream from an upstream edge of the aperture to redirect the exhaust flow through the aperture. A component is coupled to the main housing for treating exhaust flowing through the treatment zone.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
Aftertreatment system 10 includes a burner 18 that selectively increases the temperature of the exhaust by selectively igniting and combusting fuel to provide the exhaust at an elevated temperature to the rest of the system 10 provides a number of advantages, some of which will be discussed in more detail below.
Aftertreatment system 10 may also include one or more other exhaust treatment devices, such as a diesel particulate filter (DPF) 20 connected downstream from the burner 18 to receive the exhaust therefrom, and a NOx reducing device 22, such as a selective catalytic reduction catalyst (SCR) or a lean NOx trap connected downstream from the DPF 20 to receive the exhaust therefrom.
Burner 18 is operable to increase the temperature of the engine exhaust, by employing an active regeneration process for the DPF 20 wherein fuel is ignited in the burner 18 to create a flame that heats the exhaust to an elevated temperature that will allow for oxidation of the PM in the DPF 20. Additionally, in connection with such active regeneration, or independent thereof, burner 18 may be used in a similar manner to heat the exhaust to an elevated temperature that will enhance the conversion efficiency of the NOx reducing device 22, particularly an SCR. Advantageously, burner 18 may provide elevated exhaust temperatures, either selectively or continuously, independent of a particular engine operating condition, including operating conditions that produce a low temperature (<300° C.) exhaust as it exits engine 16. Thus, aftertreatment system 10 can be operated without requiring adjustments to the engine controls.
Burner 18 includes an injector 24 for injecting a suitable fuel and an oxygenator. The fuel may include hydrogen or a hydrocarbon. Injector 24 may be structured as a combined injector that injects both the fuel and oxygenator, as shown in
As shown in
A conduit 41 is positioned within housing 30 and includes an open first end 43 extending through an aperture 45 of inlet header 34. An opposite second end 47 of conduit 41 may be fixed to mixing plate 36. Alternatively, second end 47 may be unsupported. An annular volume 49 exists in the space between an inner surface 55 of housing 30 and an outer surface of conduit 41.
An injector mount 46 is fixed to inlet header 34 to provide an attachment mechanism for injector 24. A nozzle portion 52 of injector 24 extends into conduit 41 such that atomized fuel may be injected within a primary combustion chamber 54 at least partially defined by an inner cylindrical surface 57 of conduit 41. Injector 24 includes a fuel inlet 58 and an air inlet 60. When burner operation is desired, fuel is injected via fuel inlet 58 and the oxygenator is provided via air inlet 60 to inject a stream of atomized fuel. First igniter 26 is positioned downstream of inlet header 34 and is operable to combust the fuel provided by injector 24 within primary combustion chamber 54. Volume 49 is placed in fluid communication with a secondary combustion chamber 61 via a plurality of apertures 62 extending through conduit 41.
Inlet assembly 38 includes an inlet opening 70 in receipt of exhaust supplied from engine 16. Inlet assembly 38 also includes an outlet 72 in fluid communication with an aperture 74 extending through body 32. Exhaust provided from engine 16 enters inlet opening 70, travels through inlet assembly 38, exits outlet 72 and enters annular volume 49. Some of the exhaust passes through apertures 62 and enters secondary combustion chamber 61. When burner 18 is operating, the exhaust travelling through apertures 62 will be heated by the flame produced via ignition of the fuel input by injector 24. Additional unburned fuel may be present in the exhaust flowing inlet assembly 38. The unburned fuel may be ignited within secondary combustion chamber 61 by second igniter 28.
Inlet assembly 38 is sized and shaped to accept a flow of engine exhaust initially extending along an axis identified at reference numeral 86. Exhaust travels through inlet assembly 38, body 32 and exits at an outlet 88 travelling along an axis identified at reference numeral 90. Axis 86 and axis 90 extend substantially parallel to and offset from one another. This relative positioning is dictated by the other components within a vehicle equipped with exhaust gas aftertreatment system 10. In particular, the position of inlet opening 70 and the position of outlet 88 are defined by the position and volume of other vehicle components.
To accommodate the manufacturer's request, inlet assembly 38 is designed to turn the exhaust flow substantially 90 degrees from axis 86 to enter aperture 74 of body 32. Inlet assembly 38 is configured in such a manner to minimize back pressure across burner 18. To achieve these goals, inlet opening 70 includes a substantially circular shape having a first diameter and a lip 94. Inlet assembly 38, as defined by first shell 40 and second shell 42, includes a reduced diameter neck portion 96 downstream from lip 94. Further downstream, first shell 40 includes a radially outwardly extending wall portion 98 intersecting with a radially inwardly tapering wall portion 100 at an inflection point 102. Second shell 42 includes a radially inwardly extending wall portion 104 extending from lip 94 to an inflection point 106 where a wall 108 of second shell 42 is closest to axis 86. An indentation 110, including or adjacent to inflection point 106, is formed to complementarily receive a substantially cylindrically shaped portion of body 32.
As best shown in
Inlet assembly 38 may be securely fixed to body 32 via a process such as welding at the interface between land 76 and body 32. Inlet assembly 38 conforms to the shape of body 32 to minimize the packaging space required for burner 18 while changing the direction of the exhaust flow into annular volume 49 and secondary combustion chamber 61 to provide optimal burner performance.
To further assist a smooth flow from inlet opening 70 to outlet 72, inflection points 102 and 106 are substantially aligned with one another in that both points are substantially the same distance downstream from lip 94 (
The axial position of inflection points 102, 106 relative to a leading edge 122 of aperture 74 is optimized to cause exhaust flow to turn into annular volume 49 and secondary combustion chamber 61 while minimizing back pressure. In particular, inflection points 102, 106 are spaced from leading edge 122 a distance identified as distance “B”. To achieve the turning function while minimizing back pressure, distance B ranges from 15 to 55 percent of a minor axis dimension of aperture 74.
The shape and relative positioning of the inlet assembly 38, body 32 and conduit 41 define engine exhaust paths that split and recombine with one another. More particularly, exhaust gas from internal combustion engine 16 is provided to inlet opening 70. Exhaust flows from left to right when viewing
The remaining portion of exhaust gas that does not pass through apertures 62 may be characterized as travelling along a bypass flow path 132. Exhaust flows through the volume 49 between conduit 41 and body 32 downstream of apertures 62. The exhaust flowing through bypass flow path 132 cools conduit 41 and body 32 and is supplied to a mixing zone 134 for combination with the combustion flow exiting combustion flow path 130.
Mixing plate 36 extends across bypass flow path 132 to restrict an available flow area of the bypass flow path 132. A plurality of elongated apertures 138 extend through mixing plate 36 to define outlet 88. Outlet 88 is coaxially arranged with axis 90. Mixing plate 36 may be fixed to interior surface 55 of housing 30. Mixing plate 36 may include a plurality of fingers 140 to enhance turbulence and temperature distribution.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
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| Number | Date | Country | |
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| 20120124982 A1 | May 2012 | US |
