DE102013215632A1 - Exhaust gas treatment system for internal combustion engine, has exhaust pipe to receive exhaust gas from internal combustion engine and supply exhaust gas to exhaust gas treatment apparatus, and fluid delivery system to supply fluid - Google Patents

Abstract

The exhaust gas treatment system (10) comprises an exhaust pipe (14) that receives an exhaust gas from the internal combustion engine (12) and supplies the exhaust gas to an exhaust gas treatment apparatus. A fluid delivery system (32) is arranged upstream of the exhaust gas treatment device and supplies a fluid. The fluid delivery system includes a fluid injector, a fluid pipe (64) in fluid communication with the fluid injector extending into the exhaust pipe for receiving fluid from a spray tip of the fluid injector. A controller (52) is provided for pressurizing the fluid injector.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims the priority of U.S. Patent Application Ser. No. 61 / 680,826, filed Aug. 8, 2012, which is hereby incorporated by reference in its entirety.

FIELD OF FINDING

Exemplary embodiments of the invention relate to exhaust treatment systems for internal combustion engines, and more particularly to exhaust treatment systems capable of completely mixing and vaporizing injected fluids into the exhaust flow to their enhanced performance.

BACKGROUND

Internal combustion engine manufacturers must meet customer requirements while meeting various regulatory requirements for reduced emissions and improved fuel economy. An example of a way to improve fuel economy is to operate an engine with an air / fuel ratio that is lean of stoichiometry (oxygen excess). Examples of lean burn engines include compression ignition engines (diesel engines) and lean burn spark ignition engines. While lean burn engines may have improved fuel economy, however, the exhaust gas expelled from such an engine, particularly a diesel engine, may be a heterogeneous mixture containing gaseous emissions such as carbon monoxide ("CO"), unburned hydrocarbons (" KW ") and nitrogen oxides (" NOx ") as well as condensed phase materials (liquids and solids) that form particulate matter (" PM "). Catalyst compositions, typically disposed on catalyst carriers or substrates, are provided in various exhaust system devices to convert some or all of these exhaust constituents to unregulated exhaust gas components.

One exhaust treatment technology in use for high levels of particulate matter reduction, particularly in diesel engines, is the Diesel Particulate Filter ("DPF") device. There are several known filter structures used in DPF devices that have demonstrated removal efficiency of the particulate matter from the engine exhaust, such as ceramic honeycomb wall-flow filters, wound or packed fiber filters, open-cell foam filters, sintered metal foams, etc. Ceramic wall-flow filters are used in automotive applications experienced significant acceptance.

The filter is a structure for removing particulates from the exhaust gas, and as a result, the accumulation of filtered particulate matter eventually has the effect of increasing the exhaust system back pressure to which the engine is exposed. Such an increase in back pressure eventually has a negative impact on engine performance and fuel economy. To account for increases in exhaust system back pressure caused by the accumulation of particulate matter, the DPF device is periodically cleaned or regenerated. Regeneration of a DPF device in vehicle applications typically occurs automatically and is performed by an engine or other controller based on signals received by engine and exhaust system sensors. The regeneration event typically involves raising the temperature of the DPF device to levels often above 600 ° C to burn the accumulated particulates, thereby cleaning the DPF device.

One method of generating the temperatures required in the exhaust system to regenerate the DPF device is to supply unburned HC, often in the form of raw fuel, to an oxidation catalyst ("OC") device. which is arranged upstream of the DPF device. The OC device typically carries an oxidation catalyst compound that promotes oxidation of HC in an exothermic event that raises the temperature of the exhaust gas. The heated exhaust gas flows downstream to the DPF device where it burns the particulates trapped therein. Injection of the fuel into the exhaust treatment system is often accomplished using injectors similar to the fuel injectors used in engines. A common challenge for exhaust system designers is to inject the HC upstream of the OC device in a manner that allows for complete dispersion of HC to use all of the OC for oxidation and completely vaporize it to completely burn it. when it passes through the OC.

Accordingly, it is desirable to provide a HC delivery system that achieves substantially uniform mixing, distribution, and vaporization of a fluid that is injected into an exhaust of an exhaust treatment system.

SUMMARY

In an exemplary embodiment, an exhaust treatment system for an internal combustion engine includes an exhaust conduit configured to receive an exhaust gas from the internal combustion engine and deliver the exhaust gas to an exhaust treatment device. A fluid delivery system is disposed upstream of the exhaust treatment device and configured to deliver a fluid thereto. The fluid delivery system includes a fluid injector, a fluid tube in fluid communication with the fluid injector that extends radially into the exhaust conduit for receiving fluid from a spray tip of the fluid injector; a controller configured to energize the fluid injector for supplying fluid to the fluid tube, and an opening in the tube located beyond the boundary layer of exhaust gas flow in the exhaust conduit for releasing the fluid into the exhaust gas flow.

The above feature and advantages and other features and advantages of the invention will be more readily apparent from the following detailed description of the invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS AND APPENDIX

1 Figure 3 is a schematic view of an engine and exhaust treatment system embodying features of the invention;

2 that the 2A - 2H is an enlarged portion of the exhaust system of 1 Figure 11, which shows examples of fluid pipes which are features of the invention;

3 Fig. 10 is a flow chart showing flow characteristics and other features of the invention;

4 Fig. 15 is another example of a fluid pipe which is features of the invention;

5 Fig. 15 is another example of a fluid pipe which is features of the invention;

6 Fig. 15 is another example of a fluid pipe which is features of the invention;

7 Fig. 15 is another example of a fluid pipe which is features of the invention;

8th Fig. 10 is a flow chart showing further flow characteristics and other features of the invention; and

9 Fig. 3 is an illustration, partially in section, of an injector and a fluid tube illustrating features of the invention.

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, like reference numbers designate like or corresponding parts and features.

Referring to 1 is an exemplary embodiment of the invention to an exhaust treatment system 10 for the reduction of regulated exhaust components produced by an internal combustion engine, such as a diesel engine 12 , emitted. It should be noted that the diesel engine 12 is merely exemplary in nature, and that the invention described herein may be implemented in various engine systems that require an exhaust particulate filter. For ease of description, the disclosure is in the context of a diesel engine 12 discussed.

The exhaust treatment system 10 has an exhaust pipe 14 which may include various segments that serve to exhaust 16 from the diesel engine 12 to transport to the various exhaust treatment devices of the exhaust treatment system. In an exemplary embodiment, the exhaust treatment devices may include a first oxidation catalyst device ("OC1"). 18 exhibit. The OC1 18 may be a flow through metal or ceramic monolith substrate 20 have that in one intumescent mat (not shown) which expands upon heating, the substrate 20 secured and isolated. The substrate 20 is in a rigid shell or rigid canister having an inlet and an outlet in fluid communication with the exhaust conduit 14 packed. The substrate 20 has an oxidation catalyst compound (not shown) disposed thereon. The oxidation catalyst compound may be applied as a washcoat and may contain platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh) or other suitable oxidizing catalysts or a combination thereof. The OC1 18 is useful in the treatment of unburned gaseous and nonvolatile hydrocarbons and CO which are oxidized to form carbon dioxide and water.

A Selective Catalytic Reduction Device ("SCR") 22 can be downstream of the OC1 18 be arranged. In a way similar to OC1, the SCR 22 also a flow through ceramic or metal monolith substrate 24 which is wound in an intumescent mat (not shown) which expands upon heating, the substrate 24 secured and isolated. The substrate 24 is in a rigid shell or rigid canister having an inlet and an outlet in fluid communication with the exhaust conduit 14 packed. The substrate 24 has an SCR catalyst composition (not shown) applied thereto. The SCR catalyst composition preferably contains a zeolite as well as one or more base metal components such as iron ("Fe"), cobalt ("Co"), copper ("Cu"), or vanadium ("V") which can efficiently serve NOx Components in the exhaust 16 in the presence of an injected exhaust fluid, such as an ammonia ("NH ₃ ") reducing agent. The NH ₃ reducing agent 26 delivered by the reductant delivery tank 28 through the pipe 30 can be delivered to the exhaust pipe 14 at a point upstream of the SCR 22 using a fluid delivery system 32 , which is described later, to be injected. The reducing agent may be in the form of a liquid or aqueous urea solution when it is attached to the exhaust gas 16 through the fluid delivery system 32 is delivered. A mixer or turbulator 50 can also be in the exhaust pipe 14 be arranged in close close proximity to the fluid delivery system to complete mixing of the reducing agent 26 with the exhaust 16 continue to support.

In one exemplary embodiment, an exhaust filter assembly, in this case a diesel particulate filter device ("DPF"), is provided. 34 in the exhaust treatment system 10 downstream of the SCR 22 arranged and serves to the exhaust gas 16 from carbon and other particles. The DPF 34 can using a ceramic wall flow monolithic filter 36 be constructed, which is wrapped in an insulating mat, the filter 36 secures and isolates. The filter 36 can be in a rigid shell or a rigid canister with an inlet and an outlet in fluid communication with the exhaust pipe 14 be packed. exhaust 16 that in the filter 36 enters, is driven by adjacent, longitudinally extending walls (not shown) and through this wall flow mechanism becomes the exhaust gas 16 filtered by carbon and other particles. The filtered particles are in the filter 36 deposited and over time have the effect of increasing the exhaust back pressure, the diesel engine 12 is exposed. It should be noted that a ceramic wall flow monolith filter 36 merely exemplary in nature, and that the DPF 34 may have other filtering devices, such as wound or packed fiber filters, open-celled foams, sintered metal fibers, etc.

In an exemplary embodiment, the increase in exhaust backpressure caused by the accumulation of particulate matter requires the DPF 34 periodically cleaned or regenerated. Regeneration refers to the oxidation or burning of the accumulated carbon and other particles typically in a high temperature (> 600 ° C) environment and excess oxygen. For regeneration purposes, a second oxidation catalyst device ("OC2") may be used. 38 upstream of the filter 36 be arranged near its upstream end. At the in 1 the embodiment shown is the OC2 38 a flow through metal or ceramic monolith substrate 40 wrapped in an intumescent mat (not shown) which expands upon heating, the substrate 40 secured and isolated. The substrate 40 is in a canister of the DPF 34 packed. The substrate 40 has an oxidation catalyst compound (not shown) disposed thereon. The oxidation catalyst compound may be applied as a washcoat and may include platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh) or other suitable oxidizing catalysts or combinations thereof. While the embodiment described the OC2 38 in the canister of the DPF 34 Depending on the installation and other system limitations, it is conceivable that the OC2 38 may also be arranged in a separate canister (not shown) upstream of the DPF 28 is positioned. In another embodiment, the OC2 38 and the DPF 36 also in a common or one or more separate canisters and in a close coupled position relative to the engine turbocharger or the exhaust pipe 14 be arranged, wherein the SCR catalyst 24 downstream of the OC2 / DPF.

Upstream of the DPF 34 is in fluid communication with the exhaust 16 in the exhaust pipe 14 a fluid delivery system 42 arranged, which will be described below. The fluid delivery system 42 in fluid communication with the HC fluid 44 in the fuel delivery tank 46 through the fuel line 48 is configured, unburned HC fluid 44 (Raw fuel) into the exhaust stream for delivery to the OC2 38 who is the DPF 34 is assigned to introduce. A mixer or turbulator 50 can also be in the exhaust pipe 14 in close proximity to the fluid delivery system 42 be arranged to completely mix, break up, evaporate and distribute the KW with the exhaust 16 continue to support.

A controller, like a vehicle controller 52 , for example, is functional with the exhaust gas treatment system 10 connected by a signal communication with a number of sensors and monitors this. The term "controller" as used herein may refer 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 combinatorial logic circuit and / or other suitable components that provide the described functionality , In an exemplary embodiment, a back pressure sensor generates 54 upstream of the DPF 34 or between the OC 38 and the turbulator 50 a signal representing the carbon and particulate loading in the ceramic wall flow monolith filter 36 indicates. This pressure sensor 54 may also be of a delta pressure type with the downstream portion after the DPF 36 is arranged. Upon determining that the particulate loading in the DPF (which may be detected by a signal that the back pressure has reached a predetermined level indicative of the need for the DPF 34 to regenerate) activates the controller 52 the fluid delivery system 42 to KW fluid 44 in the exhaust pipe 14 to mix with the exhaust gas 16 to deliver. The fuel / exhaust gas mixture enters the OC2 38 a, wherein an oxidation of the hydrocarbon fluid 44 in the exhaust 16 and the exhaust gas temperature is raised to a level (eg,> 600 ° C) that is used to regenerate the carbon and particulate matter in the filter 36 suitable is. The controller 52 The temperature of the exothermic oxidation reaction in the OC2 38 and the ceramic wall flow monolith filter 36 through a temperature sensor 56 monitor and the KW delivery rate of the fluid delivery system 42 to maintain a predetermined temperature depending on many factors, such as the temperature upstream of the OC 38 , the exhaust gas mass flow 16 , Etc.

Now referring to the 2 and 3 and with continued reference to 1 are now the fluid delivery systems 32 and 42 described in detail. For ease of description, the following discussion is on the HC fluid delivery system 42 However, it should be understood that the description applies equally to the delivery of NH3 reducing agent to the exhaust treatment system 10 through the fluid delivery system 32 Application finds. In an exemplary embodiment, an enlarged portion of the exhaust treatment system 10 an exhaust pipe 14 adjacent the inlet end 60 the DPF device 34 In the exemplary embodiment described above, the OC2 38 directly upstream of the ceramic wall flow monolith filter 36 receives. In the illustrated embodiment, the fluid delivery system includes 42 at least one KW atomizer 62 placed in an opening in the exhaust pipe 14 is mounted. The KW atomizer 62 , which may be an injector, an evaporator, or a pump, is in fluid communication with a fluid tube 64 that extends radially into the exhaust pipe 14 extends and atomized HC fluid 44 through the spray tip 66 the KW atomizer 62 receives. In exemplary embodiments, more than 1 spray tip may be provided. If the KW atomizer 62 through the controller 52 upon determining that the ceramic wall flow monolith filter 36 the DPF device 34 requires regeneration, is energized. enters the KW fluid 44 in the fluid pipe 64 and is heated due to the location of the pipe in the exhaust gas flow, which causes the evaporation of the HC fluid 44 supported. In addition, the fuel passes through the fluid tube and at the slower moving boundary layer of the exhaust gas 16 near the outer circumference 68 the exhaust pipe 14 over and gets to a point of exhaust 16 placed, which is favorable for good mixing and for a variety of exhaust gas flow conditions. In one embodiment, the HC fluid occurs 44 in the exhaust 16 from a position that is central to the line 14 is arranged.

KW-fluid ports 70A . 70B are in the fluid tube 64 at different locations along the length of the fluid tube 64 arranged. These openings 70A . 70B can be upstream in the incoming flow of the exhaust gas 16 , downstream of the exhaust flow, or may be located in an orientation tangential to the flow of exhaust gas. The number and arrangement of HC fluid ports 70A . 70B may be due to the exhaust flow (ie, velocity, flow volume) of the respective engine 12 and exhaust treatment system 10 as well as the configuration (ie diameter, etc.) of the exhaust pipe 14 at a point where the fluid pipe 64 is arranged to be determined. Upstream openings 70A can have an entrance of the exhaust gas 16 in the fluid pipe 64 and entrainment of the HC fluid 44 for the outflow of downstream facing openings 70B for exemplary 2A . B , C, D, F, G, H allow. Only downstream openings 70B . 2E , use a negative pressure caused by the flow around the fluid pipe 64 is generated to the vapor of the hydrocarbon fluid 44 in the exhaust 16 to pull or extract that around the fluid pipe 64 flows, but becomes the vapor of the HC fluid 44 mainly by the fuel flow from the atomizer and the temperature in the exhaust gas, the evaporation and a strong expansion of the HC fluid 44 causes, to flow into the exhaust pipe 14 motivated. As in the 2A , B, F, G, H and 3 shown permits a series of HC fluid openings 70A . 70B along the length of the fluid tube 64 a substantially uniform distribution of the HC fluid vapor 44 over the diameter of the exhaust pipe 14 and thus the exhaust gas flow 16 , In one embodiment, the vapor of the HC fluid 44 over a central portion of the exhaust gas flow 16 distributed. It should be noted that KW fluid openings 70A . 70B , the central near the center line of the exhaust pipe 14 concentrated, the KW fluid 44 in the section with highest velocity of the exhaust gas flow 16 to distribute. Determining which design of the pipe to use may also be determined by the type, number and arrangement of the mixer (s) 50 which is / are selected for a particular application, as well as the diameter (area) of the gas line 14 (which can be variable along its length) and the distance of the fluid tube 64 from the OC 38 be determined.

Referring again to 2 can the fluid pipe 64 over the entire diameter of the exhaust pipe 14 or only partially extend over it. In such cases, where the pipe extends over the entire diameter of the exhaust pipe, there is an option, a second HC sputtering device 62 and spray tip 66 . 2A , B, C, D, E, and F2 at the first KW atomizer 62 and spray tip 66 Add opposite or distal end. In such cases, another fuel control or resolution for the controller 52 provided during the regeneration. However, there may be cost or design advantages to having the fuel pipe 64 only partially extends over the diameter of the exhaust pipe, as in the 2G and H is shown. In such case, a single KW atomizer will be used 62 and spray tip 66 Used to fuel to the flow of the exhaust stream 16 through the exhaust pipe 14 to deliver.

Now referring to the 4 - 7 and with continued reference to 1 Another example embodiment of the fluid delivery systems will be described 32 and 42 described in detail. Likewise, for ease of description, the following discussion is on the HC fluid delivery system 42 However, it should be understood that the description applies equally to the delivery of NH ₃ reducing agent to the exhaust treatment system 10 Application finds. In an exemplary embodiment, as in FIG 2 shown, the exhaust pipe 14 adjacent the inlet end 60 the DPF device 34 be arranged that the OC2 38 directly upstream of the ceramic wall flow monolith filter 36 receives. In the illustrated embodiment, the fluid delivery system includes 42 at least one HC injection device 80 placed in an opening in the exhaust pipe 14 mounted in a known manner. The KW injector 80 is in fluid communication with fuel passageways 86 . 4 - 7 , the fluid tube 64 , The fuel passages 86 take injected KW fluid 44 on when the injector from the controller 52 energized upon detection that the ceramic wall flow monolith filter 36 the DPF device 34 requires regeneration. The fuel passages 86 can in a massive fluid pipe 64 be drilled, with overlapping outlet sections 87 also drilled at various points along the length thereof. Once the KW fluid 44 in the fuel passages 86 in the fluid tube 64 it is due to the arrangement of the fluid pipe 64 heated in the exhaust gas flow, causing the evaporation of the HC fluid 44 supported. In addition, the fuel passes through the fuel passages in the fluid tube 64 and at the slower moving boundary layer of the exhaust gas 16 near the outer circumference 68 . 3 , the exhaust pipe 14 past. In exemplary embodiments, the use of multiple passes provides 86 ( 5 . 6 and 7 ) Advantages for a better distribution of HC fluid 44 from the spray tip 66 in front.

The fuel passages 86 open at various locations along the length of the fluid tube 64 . 5 - 7 , The fluid passages 86 can be upstream in the incoming flow of the exhaust gas 16 , downstream of the flow of exhaust gas 16 or they may be arranged in a tangential orientation to the flow of exhaust gas. The number and arrangement of fluid passages 86 is due to the exhaust gas flow (ie velocity, flow volume) of the respective engine 12 and exhaust treatment system 10 as well as the configuration (ie diameter, etc.) of the exhaust pipe 14 at the point where the fluid pipe 64 is arranged, determined. The determination of which pipe construction to use is also due to the type, number and arrangement of the mixer (s) 50 which is / are selected for a particular application, as well as the diameter (area) of the gas line 14 (which can be variable along the length) and the distance of the fluid tube 64 from the OC 38 customized.

As in the 5 - 7 is shown, allows a series of fluid passages 86 extending along the length of the fluid tube 64 open, a uniform distribution of KW fluid 44 over the diameter of the exhaust pipe and thus the exhaust gas flow 14 , It should be noted that fuel ports, which are more central near the center line of the exhaust pipe 14 are concentrated, as in 4 , the KW fluid 44 in the section with highest velocity of the exhaust gas flow 16 to distribute.

Now referring to 8th can the effect of the fluid tube 64 on the flow of exhaust 16 be seen. If the exhaust gas is the fluid pipe 64 happens, becomes a turbulent wake 88 generated. In cases where the fuel pipe 64 Having HC fluid openings or fluid passages facing in the downstream or tangential direction will produce an additional fuel mixture in the wake region 88 due to added turbulence as well as dwell time of this gas when it is currently slowing down. It should be noted that, as in 8th is shown, different fluid tube cross-sections 89A - 89D can be used. The diameter of the pipe 64 is chosen to have this effect in relation to the area of the exhaust pipe 14 and highlight the exhaust flow area for the application.

Now referring to 9 In an exemplary embodiment, an exhaust protrusion 90 outside the exhaust pipe 14 fixes and defines a through hole 92 for fluid access to the exhaust gas flow 16 , The fluid tube 64 is through the hole 92 the exhaust protrusion inserted and is in the through hole 92 through a widened upper end 94 supported. The widened upper end 94 take the spray tip 66 the KW atomizer 62 or the injector tip 82 the KW injection device 80 and then through a union nut 96 locked in place, in the thread projection 90 is screwed.

In exemplary embodiments, the distance from the sputtering device 62 and the fuel pipe 64 to the OC 38 , the design of the pipe and the design layout and number of mixers 50 based on the type of engine 12 and the desired performance characteristics of the exhaust treatment system 10 be varied.

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, but that the invention include all embodiments falling within the scope of the present application.

Claims (10)

Exhaust gas treatment system for an internal combustion engine, comprising: an exhaust pipe configured to receive an exhaust gas from the engine and to supply the exhaust gas to an exhaust treatment device; a fluid delivery system disposed upstream of the exhaust treatment device and configured to deliver a fluid thereto, the fluid delivery system comprising: a fluid injector; a fluid tube in fluid communication with the fluid injector extending into the exhaust conduit for receiving fluid from a spray tip of the fluid injector; a controller configured to energize the fluid injector to deliver fluid to the fluid tube; and an opening in the tube centrally disposed in the exhaust gas flow in the exhaust conduit to release the fluid into the exhaust gas flow. The exhaust treatment system of claim 1, wherein the exhaust treatment device comprises an oxidation catalyst and the fluid comprises unburned hydrocarbon. The exhaust treatment system of claim 1, wherein the exhaust treatment device comprises a selective catalytic reduction device and the fluid comprises an ammonia ("NH ₃ ") reducing agent. The exhaust treatment system of claim 1, wherein the fluid tube extends diametrically across the diameter of the exhaust conduit and has a second end in communication with the exhaust conduit. The exhaust treatment system of claim 4, further comprising a second fluid injector in communication with the second end of the fluid tube to deliver fluid to the fluid tube. A fluid delivery system configured to deliver fluid to an exhaust treatment device via an exhaust conduit, the fluid delivery system comprising: a fluid injector; a fluid tube in fluid communication with the fluid injector extending into the exhaust conduit for receiving a fluid from a spray tip of the fluid injector; a controller configured to energize the fluid injector to deliver fluid to the fluid tube; and an opening in the tube centrally located in the exhaust conduit to release the fluid into the exhaust conduit. The fluid delivery system of claim 6, wherein the fluid tube extends diametrically across the diameter of the exhaust conduit and has a second end in communication with the exhaust conduit. The fluid delivery system of claim 7, including a second fluid injector in communication with the second end of the fluid tube to deliver fluid to the fluid tube. The fluid delivery system of claim 6, wherein the fluid injector is a fluid evaporator. Fluid delivery system according to claim 6, wherein the opening in the tube is arranged centrally beyond the boundary layer of the exhaust gas flow in the exhaust pipe.

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