SE543916C2 - Evaporator module and exhaust aftertreatment system comprising such a module - Google Patents

Abstract

The present disclosure relates to an evaporator module for an exhaust aftertreatment system for a vehicle.The module comprises an injector shield cup (28), a flow guide (24), a mixer (22), an evaporation chamber (16), and a plurality of spacer legs (36). The mixer (22) is arranged in the evaporation chamber (16) at an upstream end of the evaporation chamber. Each of the plurality of spacer legs (36) is fixed at a first end to the upstream end of the evaporation chamber (16) and fixed at a second end to the injector shield cup (28), such that the injector shield cup is fixed at a distance from the mixer (22). The flow guide (24) is fixed to the injector shield cup (28) such that the flow guide (24) is arranged between the mixer (22) and the injector shield cup (28) at a predetermined distance from the mixer (22).The disclosure also relates to an exhaust aftertreatment system comprising such a module. The disclosure further relates to a vehicle comprising such an exhaust aftertreatment system.

Description

Evaporator module and exhaust aftertreatment system comprising such a module TECHNICAL FIELD The present disclosure relates to a module for an exhaust aftertreatment system for a vehicle,as well as an exhaust aftertreatment system comprising such a module. The disclosure further relates to a vehicle comprising such an exhaust aftertreatment system.

BACKGROUND ART Emissions standards for motor vehicles are becoming increasingly stringent. Such standardstypically specify maximum emission levels for a number of tailpipe pollutants including carbonmonoxide (CO), hydrocarbons (HC), nitrogen oxides (NOX) and particulate matter (PM). lnorder to meet the requirements ofthe present and presumably future standards, vehicles are required to be equipped with emissions reduction technologies.

Selective catalytic reduction (SCR) is an effective technology to reduce tailpipe nitrogen oxides(NOX) emissions. lt involves adding a reductant, such as ammonia, to the vehicle exhauststream. The reductant, with the aid of a catalyst, reduces NOX in the exhaust stream tonitrogen gas (NZ) and water. ln practical implementations in motor vehicles, an aqueous ureasolution is used as a reductant and this urea solution is decomposed to ammonia and carbon dioxide in the hot exhaust stream. lt is desirable to be able to remove substantially all NOX from the exhaust stream using onlySCR. However, this is not without difficulties. ln order to produce the quantities of ammoniarequired to reduce substantially all NOX, large quantities of urea solution must be injected intothe exhaust stream. To be able to utilize injected urea and reduce NOx-emission with highefficiency over the SCR, effective distribution of reductant in the exhaust stream is essential.Non-uniform distribution can lead to deposition of urea and urea by-products on surfacesdownstream ofthe injection site. ln some cases the aftertreatment system may requiredismantling in able to dislodge such deposits. I\/|oreover, ifthe reductant is not uniformly distributed over the SCR catalyst, the catalyst may need to be dimensioned to the maximum 2flux of reductant, meaning that some catalysts will be over-dimensioned, which isenvironmentally and economically wasteful. Alternatively, excess urea will have to be injectedto fully supply all catalysts with reductant. This excess urea will require the use of a larger ammonia slip catalyst in order to prevent tailpipe ammonia emissions. lt is known to provide a mixer in the exhaust aftertreatment system downstream of areductant injector. The mixer creates a rotation of the exhaust gases and provides improveddistribution ofthe reductant in the exhaust gas for any given volume of evaporation chamber.Further devices for guiding the flow of exhaust gases may also be arranged in theaftertreatment system to cooperate with the mixer and provide improved reductant distribution in the exhaust flow.

There remains a need for exhaust aftertreatment systems that provide improved distribution of reductant in the exhaust stream.

SUMMARY OF THE INVENTION The inventors of the present invention have identified a number of shortcomings in prior artsolutions for obtaining good distribution of reductant in the exhaust stream. Systems utilizinga mixer and flow guide may provide good distribution when the various components areoptimally arranged in relation to each other. However, small variations in the spatialarrangement of the components may cause significant deterioration in the performance of thesystem. For example, a deviation by a few millimetres in the distance between a flow guideand the mixer may decrease the amount of reductant being capable of being dosed to the system without causing deposition by as much as 25%. ln prior art systems the mixer and flow guide are welded to separate parts in proximity to eachother. The tolerance chain between the mixer and the guide plate is long, which affects theability to accurately control the spatial arrangement of these components, for example withregard to the distance between the components and/or the alignment ofthe components.After assembly ofthe aftertreatment system the components are enclosed in a concealed space, which limits the possibility of verifying the spatial arrangement of the components with 3relation to each other, and/or rectifying the spatial arrangement if it is found to deviate excessively.

Therefore, it is an object ofthe present invention to remedy or a||eviate at least some oftheshortcomings described above. ln particular, it would be desirable to enable a means ofdistributing reductant in the exhaust stream that provides consistently good distribution and may be easily verified.

These objects are obtained by the module for an exhaust aftertreatment system according tothe appended claims. The exhaust aftertreatment system is preferably for a vehicle. Themodule comprises: an injector shield cup, a flow guide, a mixer, an evaporation chamber, anda plurality of spacer legs. The mixer is arranged in the evaporation chamber at an end of theevaporation chamber. Each ofthe plurality of spacer legs is fixed at a first end to the end ofthe evaporation chamber and fixed at a second end to the injector shield cup, such that theinjector shield cup is fixed at a distance from the mixer. The flow guide is fixed to the injectorshield cup such that the flow guide is arranged between the mixer and the injector shield cup at a predetermined distance from the mixer.

Such a module may reduce the performance variation within the system by ensuring anoptimal and highly reproducible distance is provided between the mixer and flow guide. This isdone by ensuring that the tolerance chain between the mixer and flow guide is decreased, andby allowing the relative spatial arrangement of the mixer and flow guide to be controlledduring assembly. Verification of the spatial arrangement of the mixer and flow guide withrespect to each other may be simplified, since positioning can be verified in the relativelyaccessible module prior to insertion ofthe assembly into the concealed space ofthe exhaust aftertreatment SyStem.

The mixer, the flow guide and the injector shield cup may each be arranged coaxially with theevaporation chamber. The module permits reproducibly excellent coaxiality between these components, further assisting in ensuring good and highly reproducible performance.

The mixer, the flow guide and the injector shield cup may each be arranged normal to a longitudinal axis ofthe evaporation chamber. The module permits reproducibly excellent 4collinearity between these components, further assisting in ensuring good and highly reproducible performance.

The plurality of spacer legs may be manufactured integrally with the evaporation chamber.This provides a simple and robust means of providing spacer legs fixed to the evaporationchamber. Alternatively, or in addition, the plurality of spacer legs may be manufacturedseparately from the evaporation chamber. Such spacer legs may be affixed at the end oftheevaporation chamber. This is a material-effective means of providing an evaporation chamber having spacing legs.

The plurality of spacer legs may consists of from three to five spacer legs. The spacer legs maybe evenly distributed around a circumference ofthe evaporation chamber. Each oftheplurality of spacer legs may have a width less than 5% ofthe circumference of the evaporationchamber, preferably less than 2%. This helps ensure that the spacer legs do not unduly obstruct the flow of exhaust gases during operation.

The flow guide may be fixed to the mixer. This may further increase the robustness of themodule. The flow guide may be fixed to the mixer using fixing tabs, for example three evenly spaced fixing tabs.

The flow guide may be fixed to the injector shield cup using spacer tabs. The spacer tabs maybe integrally manufactured with the flow guide. For example, the flow guide may be fixed to the injector shield cup using from three to five spacer tabs.

According to another aspect of the invention, the objects of the invention are achieved by amethod for manufacturing a module, according to the appended claims. The method is formanufacturing a module for an exhaust aftertreatment system as disclosed herein. The method comprises the following steps.

A first assembly is provided that comprises an evaporation chamber, a mixer arranged in theevaporation chamber at an end of the evaporation chamber, and a plurality of spacer legs.Each of the plurality of spacer legs is fixed at a first end to the end of the evaporation chamber and extends from the end of the evaporation chamber to a second end.

A second assembly is provided that comprises a flow guide mounted to an injector shield cup. 5The first assembly is then fixed to the second assembly by fixing the injector shield cup to thesecond ends of the plurality of spacer legs such that the flow guide is arranged between the mixer and the injector shield cup.

Such a method allows a controllable and easily verifiable means of providing a module having a predetermined and reproducible distance between the mixer and the flow guide.

The evaporation chamber and plurality of spacer legs may be manufactured integrally bycutting a sheet of material such that when the sheet of material is rolled to form anevaporation chamber the plurality of spacer legs are provided at the end ofthe evaporationchamber. This provides a simple and robust means of furnishing an evaporation chamber having spacer legs extending from an end.

According to a further aspect of the invention, the objects of the invention are achieved by anexhaust aftertreatment system according to the appended claims. The exhaust aftertreatmentsystem is preferably for a vehicle. The exhaust aftertreatment system comprises a module asdisclosed herein, a reductant injector arranged inside of the injector shield cup, and an exhaust conduit arranged in fluid communication with the end of the evaporation chamber.

At least one of the plurality of spacer legs may be arranged in the exhaust conduit such as tobreak a flow of exhaust gas passing from the exhaust conduit to the evaporation chamberwhen in operation. By having such a placement, the dosing and distribution of reductant can be further improved.

The exhaust aftertreatment system may further comprise a particulate filter and/or a dieseloxidation catalyst. The diesel oxidation catalyst and particulate filter may be stand-alonecomponents, or the particulate filter may be provided with diesel oxidation catalyst functionality as a catalysed particulate filter.

According to yet a further aspect of the invention, the objects of the invention are achieved by a vehicle comprising an exhaust aftertreatment system as disclosed herein.

Further objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the present invention and further objects and advantages of it, the detailed description set out below should be read together with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which: Pig. 1 Pig. 2 Pig. 3 Pig. 4 Pig. 5 Pig. 6 Pig. 7 schematically illustrates a vehicle comprising an exhaust gas aftertreatment system; schematically illustrates a cross-sectional plan view of a prior art exhaust gas aftertreatment system; schematically illustrates an enlarged view of the portion of the prior artaftertreatment system in proximity to the upstream end ofthe evaporation chamber; schematically illustrates an evaporator module according to an exemplifying embodiment of the present disclosure; schematically illustrates an exhaust gas aftertreatment system according to an exemplifying embodiment of the present disclosure; schematically illustrates an enlarged view of the portion of the exemplifyingaftertreatment system in proximity to the upstream end ofthe evaporation chamber; is a flowchart illustrating an exemplifying embodiment of a method of manufacturing an evaporator module.

DETAILED DESCRIPTION The present disclosure concerns an exhaust aftertreatment system comprising an improved evaporator module for ensuring excellent and reproducible distribution of reductant in the exhaust stream during use. By reproducible it is meant that mass-manufactured examples of 7the evaporator module consistently provide excellent distribution of reductant and that there is little variation in result between different examples.

The exhaust aftertreatment system comprises at least an evaporator module, an exhaustconduit, and a reductant injector. lt may also comprise further components arrangedupstream or downstream of the named components. Upstream and downstream respectivelyrefer to positions in the exhaust aftertreatment system with reference to the typical directionof flow of exhaust gas from the engine to the tailpipe. A component is designated upstream ofanother if it is located in the exhaust system closer to the engine, whereas it is designated downstream if it is located in the exhaust system closer to the tailpipe.

The evaporator module comprises an injector shield cup, a flow guide, a mixer and anevaporation chamber. ln prior art modules comprising such components, the mixer is typicallyaffixed to the evaporation chamber, whereas the injector shield cup and flow guide aretypically affixed to another component of the exhaust aftertreatment system, such as anendcap. This results in the tolerance chain between the mixer and the flow guide beingexcessively long, i.e. the cumulative sum of all tolerances leads to excessive large tolerance inthe dimensional arrangement of the flow guide in relation to the mixer. lt has been found thatthe distribution performance of the evaporator module is highly sensitive to the dimensionalmodule ofthe mixer and flow guide, and especially with regard to the gap between thesecomponents. For example, it has been found that in systems dimensioned to be able to doseurea at relatively high rates without deposition of urea or by-products on the walls orcomponents of the evaporation module, slightly increasing the gap between the mixer and flow guide can lead to deposition at rates that are 40% lower.

The evaporator module according to the present disclosure helps overcome such issues. Themixer is arranged in the evaporation chamber at an upstream end ofthe evaporationchamber. The injector shield cup is fixed to this upstream end using a plurality of spacer legs.The flow guide is fixed to the injector shield cup. Such an arrangement has the effect ofconsiderably shortening the tolerance chain between the mixer and flow guide, making itmuch easier to ensure that spatial arrangement of the mixer relative to the flow guide is within predetermined tolerances. Furthermore, because the module is assembled prior to 8incorporation into the exhaust aftertreatment system, it is much simpler to verify that the spatial arrangement of the mixer and flow guide meet the specified requirements.

The evaporation chamber provides a volume in which reductant dosed to the exhaust streammay evaporate and distribute in the exhaust stream. The evaporation chamber may typicallybe formed of a length of pipe. lt may be provided with fins on its outer surface in order toimprove heat conduction and facilitate evaporation ofthe reductant. For example, it may beprovided with in excess of 100 fins around its outer circumference, the fins being formed forexample by corrugation and laser welding of a separate sheet of metal to the evaporation chamber.

At the upstream end ofthe evaporation chamber a mixer is arranged. The mixer may assist inproviding the exhaust stream with a rotational flow and in this manner increasing the flowlength for the exhaust gas in the evaporation chamber. The mixer is typically fixed stationaryin the evaporation chamber and typically comprises a plurality of blades or vanes extendingradially from a central portion, similar in appearance to a rotor or propeller. The mixer istypically coaxial with the evaporation chamber; that is to say that a central axis of the mixer corresponds to the central cylindrical axis of the evaporation chamber.

A plurality of spacer legs are arranged at the upstream end of the evaporation chamber. Thespacer legs are fixed at a first end to the evaporation chamber and extend longitudinally awayfrom the evaporation chamber to a second end. ln this context, by fixed it is meant eitherfastened to or fixed by virtue of being manufactured integrally with the evaporation chamber.The purpose of the spacer legs is to fix the injector shield cup in a predefined spatial relationto the mixer. As few as two spacer legs may be required to fulfil this purpose, but for stabilityand ease of assembly, typically from three to five legs are used, although more may be used ifdesired. The legs are suitably wide to provide the required stability to the arrangement, butshould not be so wide as to unduly impede the exhaust flow. Each leg may for example have awidth that is less than 5% of the circumference ofthe evaporation chamber, such as less than2% ofthe width ofthe evaporation chamber. The legs may be even distributed around thecircumference ofthe evaporation chamber. However, it may be desirable in some cases to provide an uneven distribution, for example in order to control the flow of exhaust. The legs 9may all be of even width, but they may also vary in width, for example if a specific leg is intended to re-direct exhaust flow.

The spacer legs fix the injector shield cup in place relative to the evaporation chamber andmixer. The injector shield cup is a cup-shaped component where the outside (concave) surfaceof the cup is directed towards the mixer. The reductant injector may be mounted inside (onthe concave side) ofthe cup. Exhaust gas does not have access to the inside of the cup andthus the injector is shielded from the heat and contaminants in the exhaust gas. A hole isarranged in the bottom ofthe cup to allow the reductant injector nozzle to spray reductant towards the mixer, into the exhaust stream.

A flow guide is arranged between the mixer and the injector shield cup. The flow guide assistsin directing the flow of exhaust in order to obtain effective evaporation and distribution ofreductant in the exhaust gas. The flow guide is fixed to the injector shield cup, and in thismanner is also fixed in a predetermined spatial relation with the mixer. The flow guide may forexample be fixed to the injector shield cup using a number of fixing tabs. These tabs may forexample be an integral part of the flow guide. The flow guide typically has a frustoconical(volcano-like) shape, and is typically arranged such that it progressively converges towards themixer. The flow guide may have an inner guide element (”crater”) that diverges towards the mixer.

The described module allows the evaporation chamber, mixer, flow guide and injector shieldcup to be fixed in relation to each other with relatively small tolerances. So, for example, thegap between the mixer and the flow guide may be controlled in an accurate and precisemanner. Each of the components may be aligned such that they share a common axis and areeach normal to the cylindrical axis of the evaporation chamber, i.e. they are coaxial and collinear in arrangement.

The components of the evaporation module may be manufactured from any suitable material.They may for example be made from stainless steel, which is corrosion resistant and toleratesthe temperatures prevalent in the exhaust aftertreatment system during operation. They maybe manufactured using any suitable processes, such as casting, moulding, forming or machining. The evaporator chamber may be manufactured by rolling a sheet of metal to form the Chamber. The plurality of spacer legs may be manufactured integrally to this chamber by cutting the sheet at its end to form the legs, either prior or subsequent to rolling.

The evaporation module is a component of the exhaust aftertreatment system. lt may beassembled by insertion into a pre-existing exhaust conduit in the exhaust aftertreatmentsystem, such that a proportion of exhaust gas may pass outside of the walls of the evaporationchamber. Alternatively, it may form a part of the exhaust conduit of the exhaustaftertreatment system such that substantially all exhaust gases pass through the evaporatorchamber. A further exhaust conduit is arranged to receive exhaust gases exiting theevaporation chamber and convey them downstream to downstream components such as an SCR catalyst. The SCR catalyst may be arranged as a separate module.

A diesel oxidation catalyst and particulate filter may be arranged upstream of the evaporationmodule in the aftertreatment system. These may be arranged as separate components, ormay be combined as a catalysed particulate filter. An exhaust conduit leads exhaust gasesfrom an outlet of the particulate filter to the upstream end of the evaporation chamber,passing by or through the flow guide. lt has been found to be advantageous if at least one legof the plurality of spacer legs is arranged to break the exhaust flow in the exhaust conduit, i.e.the leg faces "upstream". This may further improve the reductant dosing and distribution of the exhaust aftertreatment system.

The invention will now be described in more detail with reference to certain exemplifyingembodiments and the drawings. However, the invention is not limited to the exemplifyingembodiments discussed herein and/or shown in the drawings, but may be varied within thescope ofthe appended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate certain features.

Figure 1 shows schematically a side view of a vehicle 1 according to an embodiment of theinvention. The vehicle 1 includes a combustion engine 2, and an exhaust gas aftertreatmentsystem 4 arranged in exhaust conduit 10. The exhaust conduit 10 leads exhaust gases fromthe engine 2, through the exhaust gas aftertreatment system 4 and onwards to expel thetreated exhaust gases. The vehicle 1 may be a heavy vehicle, e.g. a truck as herein illustrated,a tractor, or a bus. The vehicle 1 may alternatively be a passenger car. The vehicle may be a hybrid vehicle comprising an electric machine (not shown) in addition to the combustion 11engine 2. The vehicle may alternatively be a marine vessel, such as a ship. The invention mayalso be used in the exhaust aftertreatment of non-vehicular engine systems also, such as in geHeFatOFS.

Figure 2 schematically illustrates an example of a prior art exhaust gas aftertreatment system4 in cross-sectional plan view. The system 4 comprises a diesel oxidation catalyst 6 andparticulate filter 8 arranged in a first length of pipe 10. ln a second length of pipe 12 anevaporation chamber 16 is arranged. Fins 18 are provided on the outside of the evaporationchamber 16 in order to improve heat transfer. An endcap 20 forms an exhaust conduitbetween the first length of pipe 10 and the second length of pipe 12. A mixer 22 is arranged inthe evaporation chamber 16 at the upstream end. A flow guide 24 is arranged immediatelyupstream of the mixer 22. The flow guide 24 is attached by fixing tabs 26 to an injector shieldcup 28. An injector 30 is arranged inside of the injector shield cup to be able to providereductant to the aftertreatment system. The injector shield cup 30 is attached to the endcap . An SCR catalyst may be arranged downstream of the exhaust aftertreatment system 4.

Due to the many manufacturing tolerances between the components to which the mixer 22and flow guide 24 are attached, the gap, relative angle and alignment of these componentsmay vary substantially, negatively impacting the ability of the system to distribute dosedreductant. This is illustrated in Figure 3, which shows an enlargement ofthe upstream portionof the evaporation chamber 16 and surrounding components from Figure 2. Due to a numberof slight deviations from the optimal position, each deviation being in itself withinmanufacturing tolerances, the relative spatial positioning of the mixer 22 and flow guide 24deviate significantly from the optimal positioning in terms of the gap g between them,alignment and angle, as illustrated by central axis 32 ofthe flow guide 24 and central axis 34 of the mixer 22.

Figure 4 schematically illustrates an exemplifying embodiment of an evaporator module 14according to the present disclosure. The evaporator module comprises an evaporationchamber 16, mixer 22, flow guide 24 and injector shield cup 28. The mixer 22 is mounted inthe upstream end ofthe evaporation chamber 16. A plurality of spacer legs 36 attach theinjector shield cup 28 to the evaporation chamber 16 and fix these components in a predetermined spatial arrangement. The flow guide 24 is affixed to the injector shield cup 28 12via fixing tabs 26, and thus the flow guide is also held in a predetermined spatial arrangementrelative to the mixer 22. lt can be seen that the arrangement ofthe mixer 22 relative to theflow guide 24 is easily inspected prior to mounting the evaporator module 14 within the exhaust aftertreatment system 4.

Figure 5 schematically illustrates an exemplifying embodiment of an exhaust aftertreatmentsystem in cross-sectional plan view, comprising an evaporator module as described herein.The system 4 comprises a diesel oxidation catalyst 6 and particulate filter 8 arranged in a firstlength of pipe 10. ln a second length of pipe 12 the evaporator module 14 is arranged. Theevaporator module 14 comprises evaporation chamber 16 having fins 18 provided on theoutside, mixer 22, flow guide 24, injector shield cup 28 and spacer legs 36. An endcap 20 formsan exhaust conduit between the first length of pipe 10 and the second length of pipe 12,together with the injector shield cup 28. An injector 30 is arranged inside of the injector shieldcup 28 to be able to provide reductant to the aftertreatment system. An SCR catalyst may bearranged downstream of the exhaust aftertreatment system 4. lt can be seen that a spacer leg36 is arranged to break a flow of exhaust entering the second length of pipe 12. This may assist in further improving distribution of reductant in the exhaust gases.

Figure 6 illustrates an enlargement ofthe upstream portion of the evaporation chamber 16and surrounding components from Figure 5. lt can be seen that due to the use of spacing legs36, the tolerance chain between the mixer 22 and flow guide 24 is shortened. This allowsthese components to be accurately and precisely positioned spatially relative to each other,with regard to gap g, alignment and angle, as illustrated by the collinearity of the central axis 32 of the flow guide 24 and central axis 34 of the mixer 22.

The evaporation module may be manufactured as follows, and as illustrated in the flowchart of Figure 7.

Step s701 denotes the start of the method of manufacturing. ln step s703 a first assembly is provided. The first assembly comprises an evaporationchamber, a mixer arranged in the evaporation chamber at an end of the evaporation chamber, and a plurality of spacer legs. Each of the plurality of spacer legs is fixed at a first end to the 13end of the evaporation Chamber and extends from the end ofthe evaporation chamber to a second end, as illustrated for example in Figure 4. ln step s705 a second assembly is provided. The second assembly comprises a flow guide mounted to an injector shield cup, as illustrated for example in Figure 4. ln step s707 the first assembly is fixed to the second assembly by fixing the injector shield cupto the second ends of the plurality of spacer legs such that the flow guide is arranged between the mixer and the injector shield cup, as illustrated for example in Figure 4.Step s. 709 denotes the end of the manufacturing method. ln an optional step s. 702, the evaporation chamber and plurality of spacer legs aremanufactured integrally by cutting a sheet of material such that when the sheet of material isrolled to form an evaporation chamber the plurality of spacer legs are provided at the end of the evaporation chamber.

Claims (2)

CLAllMS

1.A module (14) for an exhaust aftertreatment system (4), the module comprising aninjector shield cup (28), a flow guide (24), a mixer (22), an evaporation chamber (16), and a plurality of spacer legs (36), wherein the mixer (22) is arranged in the evaporation chamber (16) at an ugstream end of the evaporation chamber; whewm-:ïšiaracteršzefí in that each of the plurality of spacer legs (36) is fixed at a first endto the aigstream end of the evaporation chamber (16) and fixed at a second end to theinjector shield cup (28), such that the injector shield cup is fixed at a distance from the mixer (22), and wherein the flow guide (24) is fixed to the injector shield cup (28) such that the flowguide (24) is arranged between the mixer (22) and the injector shield cup (28) at a predetermined distance from the mixer (22). A module according to claim 1, wherein the mixer (22), the flow guide (24) and the injector shield cup (28) are each arranged coaxially with the evaporation chamber. A module according to any one of the preceding claims, wherein the mixer (22), the flowguide (24) and the injector shield cup (28) are each arranged normal to a longitudinal axis of the evaporation chamber. A module according to any one of the preceding claims, wherein the plurality of spacer legs (36) are manufactured integrally with the evaporation chamber (16). A module according to any one of claims 1-3, wherein the plurality ofspacerlegs (36) are manufactured separately from the evaporation chamber and affixed at the end ofthe evaporation chamber (16). A module according to any one of the preceding claims, wherein the plurality of spacer legs (36) consists of from three to five spacer legs. A module according to any one of the preceding claims, wherein the plurality of spacer legs (36) are evenly distributed around a circumference ofthe evaporation chamber (16). s.9.510.a)b)C)11.1

2. A module according to any one of the preceding claims, wherein each of the plurality ofspacer legs (36) has a width less than 5% of a circumference ofthe evaporation chamber, preferably less than 2%. A module according to any one of the preceding claims, wherein the flow guide (24) is fixed to the mixer (22). A method for manufacturing a module for an exhaust aftertreatment system according to any one of claims 1-9, the method comprising the steps: providing (s703) a first assembly comprising an evaporation chamber (16), a mixer (22)arranged in the evaporation chamber at an end of the evaporation chamber, and aplurality of spacer legs (36), wherein each of the plurality of spacer legs is fixed at a firstend to the end ofthe evaporation chamber and extends from the end ofthe evaporation chamber to a second end; providing (s705) a second assembly comprising a flow guide (24) mounted to an injector shield cup (28); and fixing (s707) the first assembly to the second assembly by fixing the injector shield cup(28) to the second ends of the plurality of spacer legs (36) such that the flow guide (24) is arranged between the mixer (22) and the injector shield cup (28). A method according to claim 10, wherein the evaporation chamber (16) and plurality ofspacer legs (36) are manufactured integrally (s702) by cutting a sheet of material such thatwhen the sheet of material is rolled to form an evaporation chamber the plurality of spacer legs are provided at the end ofthe evaporation chamber. An exhaust aftertreatment system (4), the exhaust aftertreatment system comprising amodule (14) according to any one of claims 1-9, a reductant injector (30) arranged insideof the injector shield cup (28), and an exhaust conduit (21) arranged in fluid communication with the end of the evaporation chamber (16). An exhaust aftertreatment system according to claim 12, wherein at least one of theplurality of spacer legs (36) is arranged in the exhaust conduit (21) such as to break a flowof exhaust gas passing from the exhaust conduit (21) to the evaporation chamber (16) when in operation. An exhaust aftertreatment system according to any one of claims 12-13, further comprising a particulate filter (8) and/or a diesel oxidation catalyst (6). A vehicle (1) comprising an exhaust aftertreatment system (4) according to any one of claims 12-14.