DE112007002861T5 - Fluid injection and mixing systems for exhaust aftertreatment devices - Google Patents

Abstract

A system for applying secondary fluids to after-treatment systems in automobiles, the system comprising:
a mixing chamber coupled to receive a portion of an exhaust stream at a mixing chamber inlet;
a secondary fluid source in fluid communication with the mixing chamber; and
a fluid distribution element positioned in a main exhaust flow conduit upstream of the exhaust aftertreatment device and coupled to an outlet of the mixing chamber, the flow distribution element operative to provide a preselected pattern of fluid flow toward an upstream surface of the aftertreatment device.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

For the present Registration becomes the priority US utility model application No. 11 / 862,293 of September 27, 2007 and the provisional US application No. 60 / 874,921 of December 14, 2006, on the Content is hereby referred to.

TERRITORY

The The present disclosure relates to exhaust aftertreatment devices. In particular, the disclosure relates to regeneration, Oxidation or reduction of emissions by such devices.

BACKGROUND

The Information in this section is only background information to the present disclosure and do not constitute prior art.

Exhaust aftertreatment systems for diesel engines that are approved for road traffic (on-highway diesel engines) typically include in future model years diesel particulate filter (DPF), NO _x adsorber (LNT = Lean _NOx -Trap) and systems for selective catalytic reduction (SCR). For the reliable function and / or preservation of the substrates used in these systems, regenerative oxidizing or reducing fluids (a secondary fluid) are needed. In most applications, DPFs require the injection of hydrocarbons (HC), for example diesel fuel, for the periodic regeneration or oxidation of trapped soot in the filter. SCR systems rely on the injection of a reductant (usually urea) upstream of the catalyst to reduce oxides of nitrogen emissions. LNTs require periodic regeneration through the use of hydrocarbon and carbon monoxide rich exhaust gases, which are normally provided by injecting excess diesel fuel into the exhaust stream. The currently common method of injecting these hydrocarbon fuels and urea is to inject into the exhaust pipe upstream of the aftertreatment device. This injection must occur at a location far enough upstream of the device to ensure that the injected fluid is sufficiently mixed, vaporized and / or hydrolyzed, the upstream linear distance typically being ten or more tube diameters.

disadvantage This conventional method results when SCR, LNT and / or DPF systems either packed in a confined space or in a housing need to be coupled with each other. The for sufficient mixing, evaporation and / or hydrolysis of the injected fluid available tube length may not be enough off, or all the back pressure will be on the aftertreatment system inadmissible high if an exhaust pipe of sufficient length is used. by virtue of the spatial restrictions Is it possible, that aftertreatment components on the track in the exhaust pipe are positioned for injecting, mixing, evaporating and / or hydrolyzing is needed, so that they affect the proper functioning of the aftertreatment devices.

It There is therefore a need for an arrangement that causes sufficient mixing, evaporation and / or hydrolysis of the injected secondary fluid in the case allows in which a suitable exhaust pipe length not available is.

OVERVIEW

The Present teachings are to an additional pipeline, alternative Pipeline routes and additional Directed devices that inject, mix, evaporate and / or hydrolyzing secondary fluids, the for Exhaust after-treatment systems are needed in motor vehicles. Such secondary fluids These include, for example, regenerating fluids or oxidizing agents Fluids or reducing fluids.

According to one Aspect of the invention is a Pipe along the aftertreatment device parallel to the exhaust stream. This tube opens laterally and upstream of the secondary fluid requiring Device substrate in the aftertreatment device. Before and while Injecting the tube is supplied with compressed air to a pressure to achieve the higher is the pressure at the point where it flows into the exhaust gas flow, and to achieve a flow rate suitable for thorough mixing, evaporation and / or hydrolyzing the secondary fluid is sufficient. At the point at which the mixing tube opens into the exhaust gas flow, holds a valve this positive pressure in the pipe. The secondary fluid is added as needed in inject this tube and open the valve as needed.

According to a second aspect of the present teachings, one or more pipes parallel to the main exhaust pipe between the engine and the aftertreatment device extend from a location from the exhaust manifold or turbocharger upstream of a turbine inlet to the point in the aftertreatment system immediately upstream of the component that injects the injected secondary fluid needed.

According to one Third aspect of the present teachings is the exhaust aftertreatment device with one extending through the substrate of the device provided central channel or a central conduit, the or the the mixing chamber for the exhaust fluid / secondary fluid contains.

Further Areas of application will become apparent from the following description. It is understood that the description and the specific examples serve only for illustration purposes and not intended for it are to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The Drawings described herein are for illustration only, without the scope of the present disclosure in any way limit.

The Objects and features of the present teachings emerge from the reading the detailed description in connection with the drawing.

1 Figure 11 is a sectional view of an exhaust after-treatment system having a variety of aftertreatment devices in a single housing, the system having a secondary fluid mixing system disposed in a parallel branch in accordance with the present teachings;

2 FIG. 3 is a partially sectioned side view of a first alternative embodiment of an exhaust aftertreatment system formed in accordance with the principles of the present disclosure; FIG.

3 Figure 4 is a partial cross-sectional view of a second alternative embodiment of an exhaust aftertreatment system formed in accordance with the principles of the present disclosure;

4A and 4B are respectively side and end views in a sectional view of the aftertreatment device of 3 wherein a regenerative fluid distribution element formed in accordance with the principles of the present disclosure is shown;

5 is a cross section of a third embodiment of an exhaust aftertreatment system according to the invention; and

6 is a perspective view of an alternative exhaust aftertreatment device with an inventively designed internal mixing chamber whose outer shell has been removed.

LONG DESCRIPTION

The The following description is merely exemplary and is not intended determines the present disclosure, its application or use limit.

1 shows an exhaust aftertreatment system 100 with a multi-purpose exhaust aftertreatment device comprising multiple elements. In the device inflowing exhaust gas is indicated by the arrow 130 , Exhaust gas flowing out of the device using the arrow 132 shown. The multi-purpose exhaust aftertreatment device comprises a first diesel oxidation catalyst or a NO _x adsorber substrate 102 , a substrate 104 for selective catalytic reduction, a second diesel oxidation catalyst or a NO _x adsorber substrate 102b , a diesel particulate filter substrate 106 and a third diesel oxidation catalyst or a NO _x adsorber substrate 102c , These substrates are each separated by a gap between the substrates, which serves to receive a secondary fluid distribution element explained below.

A urea mixing tube 106 is substantially parallel to the exhaust gas flow along the exhaust aftertreatment device and receives a combination of urea and compressed air at an inlet 108 , for mixing in a chamber 116 a line 106 , A valve 120a directs the compressed air / urea mixture into a first distribution element 122a for regenerative fluid that is between the substrates 102 and 104 is arranged and a plurality of radially oriented perforations or openings 123 that's out of line 106 incoming secondary fluid to the inlet surface of the substrate 104 to steer.

A hydrocarbon mixing tube 110 also extends substantially parallel to the exhaust gas stream and receives a mixture of hydrocarbons, for example diesel fuel, and compressed air at an inlet 112 , for mixing in a chamber 118 the line 110 , Optionally, a glow plug or another additional heating component 114 into the mixing chamber 118 extend into it. A valve 120b is used for the metered abandonment of the mixture of exhaust gas and secondary fluid in a distribution element 122b used. The wires 106 and 110 enter the exhaust treatment device laterally and upstream of the particular substrate requiring the secondary fluid. Before and during the injection, these tubes are additionally supplied with compressed air in order to achieve a pressure which is higher than the pressure at the point at which the Fluid / exhaust gas mixture flows through the device in the exhaust stream, and to achieve a flow which is sufficient for thorough mixing, evaporation and / or hydrolysis of the secondary fluid. At the point where the secondary fluid flows into the exhaust stream, a valve holds this positive pressure in the pipe. The secondary fluid is injected as needed and the valve is opened as needed.

These encounter parallel pipes the mixture of air and injected secondary fluid into the chamber between the substrates of the exhaust aftertreatment device immediately upstream of this Substrate in a series of openings that are tuned to provide the flow pattern that is above the treated substrate surface needed becomes.

Other ancillary devices may also be incorporated into this parallel piping system, including heaters to assist in the evaporation of secondary fluids, burners to assist in the regeneration of LNZs and / or DPF, and / or devices to create laminar or turbulent airfoils or to aid in mixing the exhaust gas and the secondary fluids. Alternatively, the lines, for. As the lines 106 and 110 , be physically attached to the jacket of the aftertreatment device housing in such a manner that heat transfer occurs from the aftertreatment device, thereby assisting in the heating of the air / secondary fluid mixture.

In the embodiment of 2 uses the exhaust aftertreatment system 200 additional tubes to establish a parallel exhaust gas flow into which the secondary fluid is injected. A diesel engine 202 has an exhaust manifold 204 who is in a turbocharger 206 emptied. The exhaust gas is then via an exhaust pipe 208 to an inlet 222 an exhaust aftertreatment device 220 promoted. Substantially parallel to the flow of exhaust gas through the conduit 208 is a line running 210 Also, the exhaust gas directly from an exhaust manifold 204 or optionally from a turbocharger 206 to a second inlet 224 an aftertreatment device 220 promoted. An injector 212 injects the required secondary fluid in through the line 210 moving exhaust gas flow, which then at the inlet 224 into the device 220 is directed. This mixture then flows through the substrate 226 the aftertreatment device 220 and leaves them at their outlet 228 to from a tailpipe or another exhaust pipe 230 to be included. It is thus apparent that the line 210 from a location on the exhaust manifold 204 or from a turbocharger 206 upstream of the turbine inlet to a point immediately upstream of the substrate member which requires the injected secondary fluid. Because the line 210 has its origin at a point where the pressure is much higher than the pressure immediately upstream of the substrate 226 , the exhaust gas flow through the pipe 210 , past the injector 212 and through the mixing section of the pipe 210 ensured.

In another possible configuration that is in 3 As shown, a pipe or pipes carry exhaust gas along a path parallel to the flow through an aftertreatment substrate, circumvent this and allow a diameter to length ratio sufficient for injection and thorough mixing, vaporization and / or hydrolysis of the secondary fluid. The exhaust aftertreatment system 300 includes an aftertreatment device 306 that is between an exhaust pipe 304 and a tailpipe 332 lies. The exhaust flow is indicated by the arrows 302 illustrated.

Exhaust gas reaches an inlet 308 to an entrance chamber 310 into the device 306 , From the chamber 310 the exhaust gas flows through both a substrate 326 as well as by a substantially parallel line 312 , past an injector 316 for injecting a secondary fluid into the exhaust stream, as indicated by the arrow 322 is shown. This mixture then flows into the chamber 311 the device 306 and flows through both the substrate 328 as well as back through a second parallel tube 314 , passing a second injector 318 , As by the arrow 324 is shown, the mixture then flows back into the chamber 310 for a treatment of the substrate 326 , Since this configuration does not necessarily deliver gas from a higher pressure region to a lower pressure region, an additional pumping device could be used 320 Part of the system 300 to allow sufficient flow and adequate mixing, evaporation and / or hydrolysis of the secondary fluid.

In the 4A and 4B both encounter the embodiments of the 2 and 3 the mixture of exhaust gas and secondary fluid through a series of openings 404 in a coil or helical ring 402 adjacent to the outer skin of a chamber immediately preceding the treatment aftertreatment substrate member, into the chamber. In cases where injection is needed only on a periodic basis (eg, LNT or DPF regeneration), one or more valves may be positioned in the system to introduce the exhaust flow through the parallel pipe or tubes and to interrupt.

A third embodiment of an exhaust aftertreatment system according to the invention is in 5 specified. The exhaust aftertreatment system 500 has an exhaust gas inlet pipe 502 with an injector 504 for injecting a secondary fluid into the exhaust gas stream which enters an inlet 518 the aftertreatment device 510 flows. In this embodiment, the mixing chamber is in the aftertreatment device 510 Contain a channel for receiving a mixed line 508 passing through the substrate 512 extends, is formed. in the in 5 shown special device is the exhaust outlet 520 the device 510 at the same end as the exhaust inlet. A reversal chamber 516 receives the mixture of exhaust gas and secondary fluid and forces the mixture to reverse in the opposite direction and flow through the substrate openings themselves and then to an exhaust chamber 514 to get out of the outlet 520 to be expelled.

An alternative to the aftertreatment device 510 in 5 is in 6 shown. In the arrangement of 6 For example, two tubes extending from a chamber on the front surface of the substrate of the aftertreatment device pass through the substrate of the aftertreatment device to the rear side thereof. One of these tubes transports exhaust gas through the catalyst substrate to its rear surface, where the flow reverses and moves back through the substrate itself. The second tube, after exiting the gas, transports the gas from the front surface of the substrate and reverses direction back through the inner channel of the substrate to the chamber in front of a second, downstream substrate. An example would be an SCR system followed by a DPF where secondary fluids must be injected and mixed prior to each aftertreatment device. By passing the exhaust along a path parallel to the flow through an aftertreatment device, bypassing that device and allowing a diameter to length ratio sufficient for injection, thorough mixing, vaporization and / or hydrolysis, the system of FIG 6 a proper introduction of the secondary fluid in situations where this would not normally be practicable.

Also here applies to the case that an injection of secondary fluid only on a periodic basis it is required that one or more valves be positioned in the system could be, opposite the injectors Shut off the exhaust stream.

The device 600 from 6 receives an exhaust stream from the exhaust pipe 602 , where the current is indicated by arrows 604a is shown. An exhaust gas inlet pipe 606 forms a first mixing chamber for the exhaust gas and the secondary fluid, via the injector 610 is injected into the input volume, wherein the mixing chamber through a first partition wall 608 is limited on one side. The mixture of exhaust gas and secondary fluid then moves as indicated by arrows 604b shown along the line 606 to a reversing chamber on a downstream surface of the substrate 616 wherein the reversing chamber is defined by a second partition wall 618 is limited. Then the mixture of exhaust gas and secondary fluid moves over arrows 604c back through the structure of the substrate 616 itself, to one between the substrate 616 and the partition 608 limited second injection area in which a second injector 612 another secondary fluid is injected into the exhaust stream for recirculation through a second inner conduit 614 over the substrate 616 for downstream use by another aftertreatment device located on the left side of the bulkhead 618 is like that in 6 is shown. This outflow of exhaust / secondary fluid is indicated by the arrows 604d shown.

Formed according to the invention Systems create advantages when packing the aftertreatment system in a cramped environment of the aftertreatment system and when a Combination of aftertreatment devices in a common casing need to be coupled with each other. Likewise, systems according to the invention provide for one Easy configurability in situations where in the main exhaust pipe a sufficient length for the support sufficient mixing, evaporation and / or hydrolyzing of the secondary fluid available is. Such systems allow Furthermore a more effective mixing and uniformity of the mixture in cases, in which the mixed lines with a better ratio of Length too Diameter and / or can be formed with a path, the more straight is considered the main exhaust pipe. Further, a rotatable inlet path for the secondary fluid rich Mixture in an area upstream of the aftertreatment element which is being treated. Finally, the system allows according to the present Disclosure the use of larger diameter catalyst substrates (for one more even flow and a lower system back pressure), which in many cases a Positioning the substrates close together requires, thereby Pipe sections, end cones, etc. between the substrates eliminated otherwise, for the injection and the thorough Mixing the exhaust stream with the secondary fluid used would.

The Invention based on embodiments described, which are intended as an example only. The frame The invention is defined by the appended claims.

SUMMARY

One System for the use of secondary fluids on after-treatment systems in vehicles uses a mixing chamber, the for the inclusion of a portion of an exhaust stream at a mixing chamber inlet is coupled. A secondary fluid source is coupled to the mixing chamber, and a fluid distribution element is in a middle exhaust gas flow line upstream of Exhaust aftertreatment device positioned. The fluid distribution element presents a selective one Pattern of fluid flow in Direction to an upstream located area of the Aftertreatment device.

Claims (12)

System for the use of secondary fluids Aftertreatment systems in automobiles, the system comprising: a Mixing chamber used for the inclusion of a portion of an exhaust stream coupled to a mixing chamber inlet is; a secondary fluid source, which is in fluid communication with the mixing chamber; and one Fluid distribution element located in a main exhaust gas flow line upstream of Exhaust aftertreatment device positioned and with an outlet the mixing chamber is coupled, wherein the flow distribution element is effective is for the provision of a preselected Pattern of a fluid flow towards an upstream located area the aftertreatment device. The system of claim 1, wherein the mixing chamber of the main exhaust gas flow line is disconnected. The system of claim 2, wherein the mixing chamber is a Line includes, which are substantially parallel to the main exhaust gas flow line extends. The system of claim 1, further comprising a secondary fluid injector for injecting secondary fluid from the secondary fluid source under pressure into the mixing chamber. The system of claim 1, further comprising a valve, which is positioned in the outlet of the mixing chamber and effective is to selectively fluid communication between the mixing chamber and to allow and inhibit the fluid distribution element. The system of claim 1, wherein the exhaust aftertreatment device a particulate filter and the secondary fluid a filter regeneration fluid contains. The system of claim 1, wherein the exhaust aftertreatment device a catalytic converter for selective catalytic reduction and the secondary fluid a reducing agent contains. The system of claim 1, wherein the exhaust aftertreatment device a nitrogen oxide adsorber and the secondary fluid a regeneration fluid for the converter substrate contains. The system of claim 1, wherein the mixing chamber is in a housing the aftertreatment device is positioned. The system of claim 3, wherein the mixing chamber inlet with an exhaust manifold of the vehicle is coupled. The system of claim 1, wherein the fluid distribution element a perforated conduit that includes a series of openings having regard to the upstream surface of the Aftertreatment device are positioned so that they preselected Present pattern. The system of claim 11, wherein the perforated conduit annular is.