SE2050184A1 - Catalyst Arrangement, Exhaust System, Engine, and Vehicle - Google Patents

Abstract

An engine exhaust catalyst arrangement (1) is disclosed comprising a catalyst (3) with a gas outlet section (5), and a pipe section (7) connected to the gas outlet section (5). The gas outlet section (5) and the pipe section (7) together form a gas conducting path (9) configured to conduct exhaust gas along an axial direction (ad) of the gas conducting path (9). The catalyst arrangement (1) further comprises an exhaust mixer (11) arranged in the gas conducting path (9), and a gas sensor (13) arranged downstream of the exhaust mixer (11). The exhaust mixer (11) comprises a number of guide blades (15) each comprising a pitch angle (pa) relative to the axial direction (ad). The present disclosure further relates to an engine exhaust system (4), an engine (2) comprising an engine exhaust system (4), and a vehicle (6) comprising an engine (2).

Description

Catalyst Arrangement, Exhaust System, Engine, and Vehicle TECHNICAL FIELDThe present disclosure relates to an engine exhaust catalyst arrangement. The presentdisclosure further relates to an engine exhaust system, an engine comprising an engine exhaust system, and a vehicle comprising an engine.

BACKGROUND An engine exhaust Catalyst arrangement is an exhaust emission control arrangementconfigured to reduce toxic gases and pollutants in exhaust gas from an internal combustionengine into less-toxic pollutants by catalysing a redox reaction, i.e. an oxidation and areduction reaction. Engine exhaust catalyst arrangements are usually used on spark ignitionengines, such as gasoline engines, as well as on compression ignition engines, such asdiesel engines. Environmental concerns and frequently updated legal requirements onemission levels put increasing demands on engine exhaust catalyst arrangements.Moreover, because of environmental concerns and costumer demands, fuel consumption is an important aspect of a combustion engine.

A Selective Catalytic Reduction SCR system is a type of engine exhaust catalystarrangement configured to convert nitrogen oxides of exhaust gases into diatomic nitrogenand water using a reduction agent. The reductant agent may for example compriseanhydrous ammonia, aqueous ammonia, or urea. The reductant agent is usually injected upstream of a SCR catalyst.

Some engine exhaust catalyst arrangements comprise a gas sensor arranged downstreamof a catalyst, wherein the gas sensor is configured to measure a constituent of the exhaustgas. Data from the gas sensor can be utilized as an input in the control of the combustionengine, and/or a subsystem or sub-arrangement of the combustion engine. As an example, agas sensor in the form of a nitrogen oxide sensor can be utilized in a SCR system tomeasure the amount of nitrogen oxides, also referred to as NOx, in the exhaust gasesdownstream of the SCR catalyst. Data from such a gas sensor can be used to regulate the amount of reduction agent injected upstream of the SCR catalyst of a SCR system.

A problem associated with these types of systems and arrangements is that it is difficult toobtain an accurate measurement of the constituents of the exhaust gases. An inaccurate and/or erroneous measurement of the constituents of the exhaust gases may impair the 2 functionality of the combustion engine, and/or the subsystem or sub-arrangement of thecombustion engine. ln the above given example of an SCR system, an inaccurate and/orerroneous measurement of the constituents of the exhaust gases may cause an excessiveconsumption of reduction agent or too high levels of nitrogen oxides in the exhaust gasses.Too high levels of nitrogen oxides in the exhaust gasses are harmful for the environment and may cause the engine to not fulfil legal requirements.

Moreover, generally, on today's consumer market, it is an advantage if products, such asengine exhaust catalyst arrangements and their associated systems, components, andarrangements, have conditions and/or characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Furthermore, exhaust systems and their associated components and arrangements areusually arranged in confined spaces, and it can be difficult to ensure that the componentsand arrangements thereof can be reached, for example during service or repair of the exhaust system.

SUMMARYlt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by an engine exhaustcatalyst arrangement comprising a catalyst with a gas outlet section and a pipe sectionconnected to the gas outlet section. The gas outlet section and the pipe section togetherform a gas conducting path configured to conduct exhaust gas along an axial direction of thegas conducting path. The catalyst arrangement further comprises an exhaust mixer arrangedin the gas conducting path and a gas sensor arranged downstream of the exhaust mixer. Theexhaust mixer comprises a number of guide blades each comprising a pitch angle relative to the axial direction.

Since the exhaust mixer comprises a number of guide blades each comprising a pitch anglerelative to the axial direction, a mixing of the exhaust gas can be obtained in a mannerproviding a low pressure drop over the exhaust mixer. Moreover, due to the mixing of theexhaust gas, a more accurate measurement can be performed by the gas sensor arrangeddownstream of the exhaust mixer. This because in prior art solutions lacking the exhaustmixer, a measurement is made by the gas sensor of a small proportion of the total exhaust flow. By mixing the exhaust gasses upstream of the gas sensor, a measurement can be 3 made of a mixed sample of exhaust gasses in which the amount of a particular constituent ismore representative of the amount of the constituent in the total exhaust flow. As a furtherresult thereof, a more accurate control can be performed of the combustion engine, and/or asubsystem or sub-arrangement of the combustion engine, based on data from the gas SGHSOI".

Furthermore, since a mixing of the exhaust gas can be obtained in a manner providing a lowpressure drop over the exhaust mixer, a negative effect on the fuel consumption of an engine comprising the catalyst arrangement is avoided, or at least minimized.

Moreover, due to the mixing of the exhaust gasses by the exhaust mixer, more freedom isprovided for the positioning of the gas sensor. That is, as indicated above, exhaust systemsand their associated components are usually arranged in confined spaces, and it can bedifficult to ensure that the components thereof can be reached, for example during service orrepair of the exhaust system. Moreover, in the in prior art solutions lacking the exhaust mixer,the gas sensor had to be placed at a certain region of the exhaust system to obtain decentreadings from the gas sensor. However, as indicated above, due to the mixing of the exhaustgasses by the exhaust mixer, more freedom is provided for the positioning of the gas sensor,and the gas sensor can for example be positioned at a location which facilitates service or replacement thereof.

Accordingly, an engine exhaust catalyst arrangement is provided overcoming, or at leastalleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the guide blades are configured to provide a cyclone around a centre axis of thegas conducting path. Thereby, the mixing of the exhaust gas can be obtained in a mannerproviding an even lower pressure drop over the exhaust mixer. This because a smoothtransition can be provided from a laminar flow profile into a rotational flow profile. As a further result thereof, a negative effect on the fuel consumption can be further minimized.

Optionally, the catalyst comprises a catalyst body, and wherein the gas conducting pathcomprises an unobstructed flow path between the catalyst body and the guide blades.Thereby, the mixing of the exhaust gas can be obtained in a manner providing an even lowerpressure drop over the exhaust mixer. Accordingly, as a further result thereof, a negative effect on the fuel consumption can be further minimized. 4 Optionally, the gas conducting path comprises a Catalyst section, the pipe section, and anarrowing section bet\Neen the catalyst section and the pipe section, and wherein theexhaust mixer is arranged in the narrowing section. Thereby, an even more efficient mixingof the exhaust gasses can be provided upstream of the gas sensor, while ensuring a lowpressure drop over the exhaust mixer. As a further result thereof, a more accuratemeasurement can be performed by the gas sensor arranged downstream of the exhaustmixer. Furthermore, a more accurate control can be performed of the combustion engine,and/or a subsystem or sub-arrangement of the combustion engine, based on data from the gaS SGHSOF.

Optionally, each guide blade of the number of guide blades protrudes from a delimiting wallof the gas conducting path in a direction towards a centre axis of the gas conducting path.Thereby, an efficient mixing of the exhaust gasses can be provided upstream of the gas sensor while ensuring a low pressure drop over the exhaust mixer.

Optionally, the exhaust mixer comprises a number of separate guide blades each attached toa delimiting wall of the gas conducting path. Thereby, a flexible exhaust mixer is providedhaving conditions for being adapted to different exhaust systems and/or different combustion engines in a simple manner.

Optionally, the exhaust mixer comprises a set of guide blades connected to each other via aconnector body, and wherein the set of guide blades are attached to a delimiting wall of thegas conducting path via the connector body. Thereby, an exhaust mixer is provided havingconditions and characteristics suitable for being manufactured and assembled in a cost- efficient manner.

Optionally, the set of guide blades and the connector body are formed by one piece ofcontinuous material. Thereby, an exhaust mixer is provided having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the connector body is circular or arc-shaped. Thereby, an exhaust mixer isprovided having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the gas sensor is a nitrogen oxide sensor. Thereby, an engine exhaust catalystarrangement is provided capable of providing a more accurate measurement of nitrogen oxides while ensuring a low pressure drop over the catalyst arrangement. As a further result thereof, a more accurate control can be performed of an injected amount of reduction agent upstream of the catalyst.

Optionally, the catalyst is an ammonia slip catalyst. Thereby, an engine exhaust catalystarrangement is provided capable of providing a more accurate measurement of the gassensor while ensuring a low pressure drop over the catalyst arrangement. As a further resultthereof, a more accurate control can be performed of an injected amount of reduction agent upstream of the ammonia slip catalyst.

According to a second aspect of the invention, the object is achieved by an engine exhaustsystem comprising a catalyst arrangement according to some embodiments of the present disclosure.

Since the exhaust mixer of the engine exhaust system comprises a number of guide bladeseach comprising a pitch angle relative to the axial direction, a mixing of the exhaust gas canbe obtained in a manner providing a low pressure drop over the exhaust mixer. Due to themixing of the exhaust gas, a more accurate measurement can be performed by the gassensor arranged downstream of the exhaust mixer. This because in prior art solutions lackingthe exhaust mixer, a measurement is made by the gas sensor of a small proportion of thetotal exhaust flow. By mixing the exhaust gasses upstream of the gas sensor, ameasurement can be made of a mixed sample in which the amount of a particular constituentis more representative of the amount of the constituent in the total exhaust flow. As a furtherresult thereof, a more accurate control can be performed of the combustion engine, and/or asubsystem or sub-arrangement of the combustion engine, based on data from the gas SGHSOI".

Furthermore, since a mixing of the exhaust gas can be obtained in a manner providing a lowpressure drop over the exhaust mixer, a negative effect on the fuel consumption is avoided, or at least minimized.

Moreover, due to the mixing of the exhaust gasses by the exhaust mixer, more freedom isprovided for the positioning of the gas sensor. That is, as indicated above, exhaust systemsand their associated components are usually arranged in confined spaces, and it can bedifficult to ensure that the components thereof can be reached, for example during service orrepair of the exhaust system. Moreover, in the in prior art solutions lacking the exhaust mixer,the gas sensor had to be placed at a certain region of the exhaust system to obtain decent readings from the gas sensor. However, as indicated above, due to the mixing of the exhaust 6 gasses by the exhaust mixer, more freedom is provided for the positioning of the gas sensor,and the gas sensor can for example be positioned at a location which facilitates service or replacement thereof.

Accordingly, an engine exhaust system is provided overcoming, or at least alleviating, atleast some of the above-mentioned problems and drawbacks. As a result, the above- mentioned object is achieved.

Optionally, the exhaust system comprises an injector configured to inject a reduction agentinto the exhaust system at a location upstream of the catalyst, and wherein the exhaustsystem further comprises a control arrangement configured to control the amount of injectedreduction agent based on data from the gas sensor. Thereby, an exhaust system is providedcapable of performing a more accurate control of the amount of injected reduction agentwhile ensuring a low pressure drop over the exhaust system. Accordingly, excessiveconsumption of reduction agent and too high levels of nitrogen oxides can be avoided. As afurther result thereof, an exhaust system is provided having conditions for lowering theemissions of nitrogen oxides wile ensuring a low fuel consumption of the engine. Thus, anexhaust system is provided having conditions for fulfilling, or exceeding, legal requirements of combustion engines.

According to a third aspect of the invention, the object is achieved by an engine comprisingan engine exhaust system according to some embodiments of the present disclosure.Thereby, an engine is provided capable of obtaining more accurate data from the gassensor, while ensuring a low fuel consumption of the engine. Accordingly, an engine isprovided in which excessive consumption of reduction agent and too high levels of nitrogenoxides can be avoided. As a further result thereof, an engine is provided having conditionsfor generating lower amounts of nitrogen oxides. Thus, an engine is provided having conditions for fulfilling, or exceeding, legal requirements of combustion engines.

According to a fourth aspect of the invention, the object is achieved by a vehicle comprisingan engine according to some embodiments of the present disclosure. Thereby, a vehicle isprovided having conditions for generating lower amounts of nitrogen oxides, while ensuring a low fuel consumption of the vehicle.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGSVarious aspects of the invention, including its particular features and advantages, will bereadily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 schematically illustrates an internal combustion engine, according to someembodiments, Fig. 2 illustrates a cross section of a gas outlet section of an ammonia slip catalyst of theengine illustrated in Fig. 1, and a pipe section connected to the gas outlet section, Fig. 3 illustrates a perspective view of a narrowing section and an exhaust mixer of a catalystarrangement according to the embodiments illustrated in Fig. 2, Fig. 4 illustrates a second perspective view of the narrowing section and the exhaust mixer ofthe catalyst arrangement according to the embodiments illustrated in Fig. 2 and Fig. 3, Fig. 5 illustrates a perspective view of a narrowing section and an exhaust mixer according tosome further embodiments, Fig. 6 illustrates a catalyst arrangement comprising an exhaust mixer according to somefurther embodiments of the present disclosure, Fig. 7 illustrates a perspective view of the exhaust mixer illustrated in Fig. 6, and Fig. 8 illustrates a vehicle according to some embodiments.

DETAILED DESCRIPTIONAspects of the present invention will now be described more fully. Like numbers refer to likeelements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 schematically illustrates an internal combustion engine 2, according to someembodiments. For the reason of brevity and clarity, the internal combustion engine 2 is insome places herein referred to as the “combustion engine 2”, or simply the “engine 2”.According to the illustrated embodiments, the engine 2 is a diesel engine, i.e. a type ofcompression ignition engine. According to further embodiments, the engine 2, as referred toherein, may be another type of compression ignition engine, or an Otto engine with a spark-ignition device, wherein the Otto engine may be configured to run on gas, petrol, alcohol, similar volatile fuels, or combinations thereof.

The engine 2 comprises an engine exhaust system 4. The engine exhaust system 4 is insome places herein referred to as the “exhaust system 4” for the reason of brevity and clarity.

The exhaust system 4 comprises a Selective Catalytic Reduction system 8. Selective 8 Catalytic Reduction is sometimes abbreviated “SCR”, which abbreviation is used in someplaces herein for describing “Selective Catalytic Reduction”. The SCR system comprises adiesel oxidation catalyst 10. The diesel oxidation catalyst 10 is configured to catalyticallyoxidize hydrocarbons and carbon monoxide with oxygen to form carbon dioxide and water.The SCR system 8 further comprises a diesel particulate filter 12 arranged downstream ofthe diesel oxidation catalyst 10. The diesel particulate filter 12 is configured to remove dieselparticulate matter and soot from the exhaust gasses. Moreover, the SCR system 8 comprises a SCR catalyst 14 arranged downstream of the diesel particulate filter 12.

Furthermore, the SCR system 8 comprises an injector 33 arranged upstream of the SCRcatalyst 14 and downstream of the diesel particulate filter 12. The injector 33 is configured toinject a reduction agent 34 from a reduction agent tank 36 into the exhaust system 4 at alocation upstream of the SCR catalyst 14. The reduction agent 34 may comprise anhydrousammonia, aqueous ammonia, or urea. The SCR catalyst 14 is configured to convert nitrogenoxides of exhaust gases into diatomic nitrogen and water using the reduction agent 34. TheSCR system 8 further comprises an ammonia slip catalyst 3 arranged downstream of theSCR catalyst 14. The ammonia slip catalyst 3 is configured to oxidize excess ammonia fromthe SCR catalyst 14.

The SCR system 8 further comprises t\No nitrogen oxide sensors 13, 16, i.e. gas sensors 13,16. One of the nitrogen oxide sensors 16 is arranged upstream of the diesel oxidationcatalyst and one of the nitrogen oxide sensors 13 is arranged downstream of the ammoniaslip catalyst 3. The exhaust system 4 further comprises a control arrangement 35 configuredto control the amount of injected liquid reduction agent 34 based on data from the nitrogenoxide sensors 13, 16. The exhaust system 4 further comprises a muffler 28 arranged downstream of the ammonia slip catalyst 3 and downstream of the nitrogen oxide sensor 13.

Fig. 2 illustrates a cross section of a gas outlet section 5 of the ammonia slip catalyst 3illustrated in Fig. 1 and a pipe section 7 connected to the gas outlet section 5. Below theammonia slip catalyst 3 is referred to as “the catalyst 3”. Moreover, the catalyst 3 and thepipe section 7 connected to the gas outlet section 5 of the catalyst is referred to as an engineexhaust catalyst arrangement 1. The engine exhaust catalyst arrangement 1 is in someplaces herein referred to as “the catalyst arrangement 1” for the reason of brevity and clarity.The gas outlet section 5 and the pipe section 7 together form a gas conducting path 9. Thegas conducting path 9 is configured to conduct exhaust gas along an axial direction ad of thegas conducting path 9. The axial direction ad of the gas conducting path 9 coincides with a centre axis ca of the gas conducting path 9. Moreover, the axial direction ad of the gas 9 conducting path 9 coincides with an average flow direction fd of gas through the gas conducting path 9.

As seen in Fig. 2, the catalyst arrangement 1 further comprises an exhaust mixer 11,according to some embodiments of the present disclosure. The exhaust mixer 11 is arrangedin the gas conducting path 9. The catalyst arrangement 1 further comprises a gas sensor 13arranged downstream of the exhaust mixer 11. As understood from the herein described, thegas sensor 13 i||ustrated in Fig. 2 is a nitrogen oxide sensor 13, i.e. a gas sensor 13configured to measure the amount of nitrogen oxides in the exhaust. However, according tofurther embodiments, the gas sensor 13 may be another type of gas sensor, as is further explained herein.

As indicated in Fig. 2, the exhaust mixer 11 comprises a number of guide blades 15 eachcomprising a pitch angle pa relative to the axial direction ad. The pitch angle pa of eachguide blade 15 can be defined as an angle of attack of the guide blade 15 relative to the axialdirection ad of the gas conducting path 9. The pitch angle pa can be measured relative to theaxial direction ad, or relative to a plane perpendicular the axial direction ad. Moreover, thepitch angle pa of each guide blade 15 can be defined as the angle pa between a bladesurface of the guide blade 15 and the axial direction ad. Furthermore, the pitch angle pa ofeach guide blade 15 can also be defined as the angle pa between a blade surface of theguide blade 15 and the flow direction fd of the gas flowing towards the guide blade 15.However, as explained herein, the flow direction fd of the gas flowing towards the guideblades 15 is parallel to the axial direction ad of the gas conducting path 9. According to someembodiments, the pitch angle pa of each guide blade 15 is within the range of 3 degrees -87 degrees or is within the range of 5 degrees - 85 degrees. Since the exhaust mixer 11comprises a number of guide blades 15 each comprising a pitch angle pa relative to the axialdirection ad, a mixing of the exhaust gasses is obtained while a small pressure drop, i.e. alow flow resistance, is provided over the exhaust mixer 11. This because a smooth transitionis provided from a laminar flow profile into a rotational flow profile, as is further explained herein.

As can be seen in Fig. 2, the catalyst 3 comprises a catalyst body 17. The catalyst body 17 isan active part of the catalyst 3 meaning that the catalyst body 17 is configured to catalyse areaction between constituents in the exhaust flow. The catalyst body 17 comprises a numberof adjacent elongated cells 17' extending in the axial direction ad of the catalyst body 17. Theelongated cells 17' significantly increases the active surface area of the catalyst body 17.

Due to the elongated cells 17', a laminar flow profile is provided directly downstream of the Catalyst body 17. When the exhaust gas is reaching a guide blade 15, the laminar flow alongthe axial direction ad is converted into a rotational flow around the centre axis ca of the gasconducting path 9. This because of the pitch angles pa of the guide blades 15 and becausethe exhaust mixer 11 according to the illustrated embodiments comprises a number of guideblades 15 positioned around the centre axis ca of the gas conducting path 9. Thus, accordingto the illustrated embodiments, the guide blades 15 are configured to provide a cyclone around a centre axis ca of the gas conducting path 9.

Due to these features, a mixing is provided of the exhaust gas flowing from the catalyst body17 before the exhaust gas is reaching the gas sensor 13 in a manner providing a lowpressure drop over the exhaust mixer 11. Due to the mixing, a more accurate measurementcan be performed by the gas sensor 13 arranged downstream of the exhaust mixer 11. Thisbecause in prior art solutions lacking the exhaust mixer 11, a measurement is made by thegas sensor 13 of a small proportion of the total exhaust flow. By mixing the exhaust gassesupstream of the gas sensor 13, a measurement can be made of a mixed sample of exhaustgasses in which the amount of a particular constituent is more representative of the amountof the constituent in the total exhaust flow. As mentioned above, according to the illustratedembodiments, the gas sensor 13 is a nitrogen oxide sensor 13. Accordingly, due to thesefeatures, a more accurate control can be performed by the control arrangement 35,illustrated in Fig. 1, of the amount of reduction agent 34 injected into the exhaust system 4upstream of the catalyst 3. Thereby, excessive consumption of reduction agent 34 and toohigh levels of nitrogen oxides can be avoided. Since the mixing of exhaust gas is obtained ina manner providing a low pressure drop over the exhaust mixer 11, a negative effect on the fuel consumption is avoided, or at least minimized.

As can be seen in Fig. 2, according to the illustrated embodiments, the guide blades 15comprise a greater pitch angle pa, i.e. a greater attack angle pa, relative to the axial directionad, at a trailing portion of the guide blades 15, than at a leading portion of the guide blades15, seen along the flow direction fd of the gas conducting path 9. ln this manner, an evensmoother transition is obtained from the laminar flow profile into the rotational flow profile,which further ensures a low pressure drop over the exhaust mixer 11. Moreover, as can beseen in Fig. 2, the gas conducting path 9 comprises an unobstructed flow path between thecatalyst body 17 and the guide blades 15. ln this manner, a low pressure drop is further ensured over the exhaust mixer 11.

The gas conducting path 9 comprises a catalyst section 19, the pipe section 7, and a narrowing section 21 between the catalyst section 19 and the pipe section 7. As seen in Fig. 11 2, the Catalyst section 19 has a greater cross sectional area than the pipe section 7. Thecentre axis ca of the gas conducting path 9, as referred to herein, coincides with a centreaxis ca of the catalyst section 19, a centre axis ca of the pipe section 7, and a centre axis caof the narrowing section 21. According to the illustrated embodiments, the exhaust mixer 11is arranged in the narrowing section 21 bet\Neen the catalyst section 19 and the pipe section7. Thereby, an even more efficient mixing of the exhaust gasses can be provided upstream of the gas sensor 13, while ensuring a low pressure drop over the exhaust mixer 11.

Fig. 3 illustrates a perspective view of the narrowing section 21 and the exhaust mixer 11 ofthe catalyst arrangement 1 according to the embodiments illustrated in Fig. 2. As clearlyseen in Fig. 2, the exhaust mixer 11 comprises a number of guide blades 15 positionedaround the centre axis ca of the narrowing section 21. According to the illustratedembodiments, the exhaust mixer 11 comprises ten guide blades 15. However, the exhaust mixer 11 may comprise another number of guide blades 15, as is further explained herein.

As can be seen in Fig. 3, each guide blade 15 of the number of guide blades 15 protrudesfrom a delimiting wall 23 of the gas conducting path 9 in a direction towards a centre axis caof the gas conducting path 9. ln this manner, the guide blades 15 will provide a cyclonearound the centre axis ca in an efficient manner when gas is flowing through the gasconducting path 9. According to the illustrated embodiments, the delimiting wall 23 of the gas conducting path 9 is a delimiting wall 23 of the narrowing section 21.

Moreover, according to the embodiments illustrated in Fig. 2 and Fig. 3, the exhaust mixer 11comprises a number of separate guide blades 15 each attached to the delimiting wall 23 of the gas conducting path 9.

Fig. 4 illustrates a second perspective view of the narrowing section 21 and the exhaustmixer 11 of the catalyst arrangement 1 according to the embodiments illustrated in Fig. 2 andFig. 3. ln Fig. 4, the narrowing section 21 is illustrated in a viewing direction coinciding withthe centre axis ca of the narrowing section 21. ln Fig. 4, also the gas sensor 13 of thecatalyst arrangement is visible. Moreover, as can be seen in Fig. 4, a respective end portion15' of the guide blades 15 protrude through a respective aperture 22 provided in a wall of thenarrowing section 21. The respective guide blade 15 may be attached to the wall of thenarrowing section 21 by welding the respective end portion 15' to surfaces surrounding theaperture 22. ln this manner, the guide blades 15 are attached to the narrowing portion 21 in a rigid manner and leakage of exhaust gas through the apertures 22 is avoided. 12 Furthermore, as is clearly visible in Fig. 4, each guide blade 15 of the number of guideblades 15 protrudes in a direction towards the centre axis ca of the gas conducting path 9. lnthis manner, a guide blades 15 provide a cyclone around the centre axis ca of the gasconducting path 9 in an efficient manner when gas is flowing through the gas conductingpath 9.

Fig. 5 i||ustrates a perspective view of a narrowing section 21 and an exhaust mixer 11according to some further embodiments. Fig. 5 i||ustrates the flexible nature of the exhaustmixer 11 according to the embodiments i||ustrated in Fig. 2 - Fig. 4. According to theembodiments i||ustrated in Fig. 5, the exhaust mixer 11 comprises three guide blades 15.The guide blades 15 of the exhaust mixer 11 i||ustrated in Fig. 5 comprises the samefeatures, functions, and advantages as the guide blades 15 of the exhaust mixer 11explained with reference to Fig. 2 - Fig. 4. That is, according to the embodiments i||ustratedin Fig. 5, the exhaust mixer 11 comprises three separate guide blades 15 each attached to the de|imiting wall 23 of the gas conducting path 9.

That is, according to these embodiments, a number of guide blades 15, and the positionsthereof, can be selected when designing a particular exhaust system. According to thei||ustrated embodiments, three guide blades 15 have been positioned adjacent to each otherat a sector of the gas conducting path 9 ensuring mixing of exhaust gas before the exhaustgas is reaching the gas sensor 13. Moreover, the three guide blades 15 have beenpositioned in a manner ensuring a cyclone around the centre axis ca of the gas conductingpath 9 downstream of the guide blades 15. By using only three guide blades 15 the pressuredrop over the exhaust mixer can be further minimized which further reduces the impact on the fuel consumption of an engine comprising the exhaust mixer 11.

As understood from the above described, another number of guide blades 15 may beselected, such as one, two, four, five, or the like, for example based on the mixing needupstream of the gas sensor 13. Moreover, such guide blades 15 can be positioned atpositions ensuring mixing of exhaust gas before the exhaust gas is reaching the gas sensor13. ln this manner, the exhaust mixer 11 can be adapted to different exhaust systems anddifferent engines based on the need of mixing so as to ensure accurate measurements of a gas sensor 13 and a low pressure drop over the exhaust mixer 11.

Fig. 6 i||ustrates a catalyst arrangement 1 comprising an exhaust mixer 11 according to somefurther embodiments of the present disclosure. The catalyst arrangement 1 according to the embodiments i||ustrated in Fig. 6 comprises the same features, functions, and advantages as 13 the catalyst arrangement 1 illustrated in Fig. 2, with some exceptions explained below.According to the embodiments illustrated in Fig. 6, the exhaust mixer 11 of the catalystarrangement 1 is positioned downstream of the narrowing section 21. That is, according tothese embodiments, the exhaust mixer 11 is arranged at an inlet section of the pipe section7.

Also in these embodiments, the exhaust mixer 11 comprises a number of guide blades 15each comprising a pitch angle pa relative to the axial direction ad. The guide blades 15 havea curved wing-shaped profile relative to the axial direction ad. That is, as can be seen in Fig.6, the angle of attack, i.e. the pitch angle pa, relative to the axial direction ad increases alongthe surface of the guide blades 15 seen along the flow direction fd of gas through the gasconducting path 9. ln this manner, a smooth transition can be provided from a laminar flowprofile into a rotational flow profile downstream of the exhaust mixer 11 ensuring a low pressure drop over the exhaust mixer 11.

Fig. 7 illustrates a perspective view of the exhaust mixer 11 illustrated in Fig. 6. As seen inFig. 7, the exhaust mixer 11 comprises a set of guide blades 15 connected to each other viaa connector body 25. According to the illustrated embodiments, the set of guide blades 15and the connector body 25 are formed by one piece of continuous material, wherein theconnector body 25 is circular. According to further embodiments, the exhaust mixer 11 maycomprise two or more connector bodies 25 each comprising a number of guide blades 15.According to such embodiments, as well as in other embodiments explained herein, the connector body 25 may be arc-shaped.

According to the illustrated embodiments, the exhaust mixer 11 comprises nine guide blades15. However, according to further embodiments, the exhaust mixer 11 may comprise another number of guide blades 15, such as a number between one and t\Nenty guide blades 15.

As seen in Fig. 6, the set of guide blades 15 are attached to a delimiting wall 23 of the gasconducting path 9 via the connector body 25. Due to these features, an exhaust mixer 11 isprovided allowing a fast and cost-efficient assembly of an exhaust system comprising the exhaust mixer 11.

Fig. 8 illustrates a vehicle 6 according to some embodiments. The vehicle 6 comprises acombustion engine 2 according to the embodiments illustrated in Fig. 1. The combustionengine is configured to provide motive power to the vehicle 6 via wheels 18 of the vehicle 6.

According to the illustrated embodiments, the vehicle 6 is a truck. However, according to 14 further embodiments, the vehicle 6, as referred to herein, may be another type of manned orunmanned vehicle for land or water based propulsion such as a lorry, a bus, a constructionvehicle, a tractor, a car, a ship, a boat, or the like. Moreover, the combustion engine 2, asreferred to herein may not be a vehicle engine 2, i.e. an engine 2 for a vehicle 6. lnstead, thecombustion engine 2, as referred to herein, may be a stationary engine, such as a combustion engine connected to an electrical generator for generating electricity, or the like.

The control arrangement 35 illustrated in Fig. 1 may comprise a calculation unit Which maytake the form of substantially any suitable type of processor circuit or microcomputer, e.g. acircuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit(CPU), a processing unit, a processing circuit, a processor, an Application Specific IntegratedCircuit (ASIC), a microprocessor, or other processing logic that may interpret and executeinstructions. The herein utilised expression “calculation unit” may represent a processingcircuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 35 may further comprise a memory unit, Wherein the calculationunit may be connected to the memory unit, which may provide the calculation unit with, forexample, stored program code and/or stored data which the calculation unit may need toenable it to do calculations. The calculation unit may also be adapted to store partial or finalresults of calculations in the memory unit. The memory unit may comprise a physical deviceutilised to store data or programs, i.e., sequences of instructions, on a temporary orpermanent basis. According to some embodiments, the memory unit may compriseintegrated circuits comprising silicon-based transistors. The memory unit may comprise e.g.a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile ornon-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM(Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement 35 may be connected to components of the engine 2, or a vehiclecomprising the engine 2, for receiving and/or sending input and output signals. These inputand output signals may comprise waveforms, pulses, or other attributes which the inputsignal receiving devices can detect as information and which can be converted to signalsprocessable by the control arrangement 35. These signals may then be supplied to thecalculation unit. One or more output signal sending devices may be arranged to convertcalculation results from the calculation unit to output signals for conveying to other parts of the vehicle's control system and/or the component or components for Which the signals are intended. Each of the connections to the respective component for receiving and sendinginput and output signals may take the form of one or more from among a cable, a data bus,e.g. a CAN (controller area network) bus, a MOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the exhaust system 4 comprises a control arrangement 35but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

Control systems in modern engines generally comprise a communication bus systemconsisting of one or more communication buses for connecting a number of electronic controlunits (ECUs), or controllers, to various components on board the engine. Such a controlsystem may comprise a large number of control units and taking care of a specific functionmay be shared between two or more of them. Engines of the type here concerned aretherefore often provided with significantly more control arrangements than depicted in Fig. 1, as one skilled in the art will surely appreciate. lt is to be understood that the foregoing is illustrative of various example embodiments andthat the invention is defined only by the appended claims. A person skilled in the art willrealize that the example embodiments may be modified, and that different features of theexample embodiments may be combined to create embodiments other than those describedherein, without departing from the scope of the present invention, as defined by the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one ormore stated features, elements, steps, components, or functions but does not preclude thepresence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims (5)

1. An engine exhaust Catalyst arrangement (1) comprising:- a catalyst (3) with a gas outlet section (5), and- a pipe section (7) connected to the gas outlet section (5),wherein the gas outlet section (5) and the pipe section (7) together form a gasconducting path (9) configured to conduct exhaust gas along an axial direction (ad) ofthe gas conducting path (9), and wherein the catalyst arrangement (1 ) furthercomprises:- an exhaust mixer (11) arranged in the gas conducting path (9), and- a gas sensor (13) arranged downstream of the exhaust mixer (11),wherein the exhaust mixer (11) comprises a number of guide blades (15) each comprising a pitch angle (pa) relative to the axial direction (ad). The catalyst arrangement (1) according to c|aim 1, wherein the guide blades (15) are configured to provide a cyclone around a centre axis (ca) of the gas conducting path (9). The catalyst arrangement (1) according to c|aim 1 or 2, wherein the catalyst (3)comprises a catalyst body (17), and wherein the gas conducting path (9) comprises an unobstructed flow path between the catalyst body (17) and the guide blades (15). _ The catalyst arrangement (1) according to any one of the preceding claims, wherein the gas conducting path (9) comprises a catalyst section (19), the pipe section (7), and anarrowing section (21) between the catalyst section (19) and the pipe section (7), and wherein the exhaust mixer (11) is arranged in the narrowing section (21). The catalyst arrangement (1) according to any one of the preceding claims, whereineach guide b|ade (15) of the number of guide blades (15) protrudes from a de|imitingwall (23) of the gas conducting path (9) in a direction towards a centre axis (ca) of the gas conducting path (9). The catalyst arrangement (1) according to any one of the preceding claims, wherein theexhaust mixer (11) comprises a number of separate guide blades (15) each attached to a de|imiting wall (23) of the gas conducting path (9). _ The catalyst arrangement (1) according to any one of the claims 1 - 5, wherein the exhaust mixer (11) comprises a set of guide blades (15) connected to each other via a 10. 11. 1

2. 1

3. 1

4. 1

5. 17 connector body (25), and wherein the set of guide blades (15) are attached to a delimiting wall (23) of the gas conducting path (9) via the connector body (25). The catalyst arrangement (1) according to claim 7, wherein the set of guide blades (15) and the connector body (25) are formed by one piece of continuous material. The catalyst arrangement (1) according to claim 7 or 8, wherein the connector body (25) is circu|ar or arc-shaped. The catalyst arrangement (1) according to any one of the preceding claims, wherein the gas sensor (13) is a nitrogen oxide sensor. The catalyst arrangement (1) according to any one of the preceding claims, wherein the catalyst (3) is an ammonia slip catalyst (3). An engine exhaust system (4) comprising a catalyst arrangement (1) according to any one of the preceding claims. The engine exhaust system (4) according to claim 12, wherein the exhaust system (4)comprises an injector (33) configured to inject a reduction agent (34) into the exhaustsystem (4) at a location upstream of the catalyst (3), and wherein the exhaust system (4)further comprises a control arrangement (35) configured to control the amount of injected reduction agent (34) based on data from the gas sensor (13). An engine (2) comprising an engine exhaust system (4) according to claim 13. A vehicle (6) comprising an engine (2) according to claim 14.