WO2016024903A1

WO2016024903A1 - Exhaust aftertreatment system and vehicle comprising means for capturing catalyst poisons

Info

Publication number: WO2016024903A1
Application number: PCT/SE2015/050851
Authority: WO
Inventors: Ali SARAMAT; Sandra DAHLIN; Hanna Lind; Henrik Eriksson; Marita Nilsson; Klas EURENIUS; Ulf NYLÉN
Original assignee: Scania CV AB
Current assignee: Scania CV AB
Priority date: 2014-08-14
Filing date: 2015-08-05
Publication date: 2016-02-18
Anticipated expiration: 2017-02-14
Also published as: DE112015003236T5; CN106574531B; SE538254C2; CN106574531A; SE1450943A1

Abstract

An exhaust aftertreatment system (1) for a vehicle (100) comprises an exhaust aftertreatment device (3) and an exhaust channel 4 arranged between the vehicle's combustion engine (2) and the exhaust aftertreatment device. At least one elongated element (9) is arranged in the exhaust channel, in order to catch chemical toxins, which may otherwise deactivate a catalyst in the exhaust aftertreatment device.

Description

EXHAUST AFTERTREATMENT SYSTEM AND VEHICLE COMPRISING MEANS FOR CAPTURING CATALYST POISONS

TECHNICAL FIELD

The present invention relates to an exhaust aftertreatment system for exhausts from a combustion engine, such exhaust aftertreatment system comprising an exhaust

aftertreatment device comprising at least one catalyst adapted to purify exhausts, for example an exhaust aftertreatment device comprising at least one diesel oxidation catalyst (DOC) and one selective catalytic reduction catalyst (SCR). The invention also relates to a vehicle comprising a combustion engine and an exhaust aftertreatment system.

BACKGROUND A combustion engine burns a mix of air and fuel in order to generate a driving torque. The combustion process generates exhausts, which are emitted from the combustion engine. These exhausts are led via an exhaust conduit to an exhaust outlet arranged at the

downstream end of the exhaust conduit, from which the exhausts are emitted into the environment. The exhausts from the combustion engine contain among others nitrous exhausts (NO_x), carbon dioxide (C0₂), carbon monoxide (CO) and particles. NO_x is a generally accepted generic name for describing the nitrous exhausts that primarily comprise nitrogen oxide (NO) and nitrogen dioxide (N0₂). Before the exhaust gas is emitted into the environment via the exhaust conduit's exhaust outlet, the exhaust gas is made to pass through an exhaust aftertreatment device arranged in the exhaust conduit, which aftertreatment device usually comprises one or several catalysts, one or several particulate filters for the purification of the exhausts and potentially a silencing agent, which dampens the noise caused by the exhausts. The exhausts are led from the combustion engine to the exhaust aftertreatment device via an exhaust channel. The exhaust aftertreatment device usually comprises a diesel oxidation catalyst (DOC-catalyst) mainly adapted to oxidise hydrocarbons, but also carbon monoxide and nitrogen monoxide. Further, the exhaust treatment system usually comprises a selective catalytic reduction catalyst (SCR-catalyst), in which a reductant and NO_x may react and be converted into nitrogen and water, and thus reduce the amount of NO_x emitted into the atmosphere. The reductant is usually a urea-based solution, such as Adblue^®, and is injected into the exhaust conduit upstream of the SCR-catalyst. The exhaust aftertreatment device usually also comprises one or several diesel particulate filters (for example a catalytically coated soot filter CSF, Catalysed Soot Filter), to catch and oxidise for example soot particles. Other types of catalysts may also be used in an exhaust aftertreatment device, such as an ammonia slip catalyst (ASC).

The various components of the exhaust aftertreatment device are arranged inside a joint house which is gas-proof, except for one exhaust inlet arranged in the house, to which the exhaust channel from the combustion engine is connected, one exhaust outlet from which the purified exhausts are allowed to be led further into the surrounding atmosphere via the exhaust conduit outlet, and potential connections for supply and removal of compositions used in the various components, such as for example a urea-based solution for the SCR.

The diesel oxidation catalyst is often arranged upstream of an SCR-catalyst in order thus to oxidise hydrocarbons, carbon monoxide and nitrogen monoxide before these reach the SCR- catalyst, since they may otherwise impact the efficiency of the SCR-catalyst. It is actually common for the diesel oxidation catalyst to be the first component in the exhaust

aftertreatment device. The diesel oxidation catalyst is thus often exposed to a large amount of substances and compounds that may cause poisoning and deactivation of the diesel oxidation catalyst. In exhaust aftertreatment devices where the diesel oxidation catalyst is not the first catalyst in the device, the first catalyst exposed to the exhausts will naturally be the one exposed to the greatest load of chemical toxins in the exhausts.

Sulphur poisoning of the diesel oxidation catalyst is a known problem within the technical area. The solution to this problem is usually to temporarily increase the temperature of the exhausts, so that the sulphur coating dissolves or disintegrates. Prior art also provides for trying to catch sulphur before it reaches the diesel oxidation catalyst, by arranging a suitable component for this purpose in the exhaust aftertreatment device. US 2009/0107121 Al describes an exhaust aftertreatment system comprising a catalyst that functions like an SO_x-trap, an oxidation catalyst, a particulate filter and an NO_x SCR-catalyst. The catalyst functioning like an SO_x-trap consists of a honeycomb structure with several passages extending in the axial direction of the catalyst. Furthermore, this catalyst has a coating, comprising for example an alkali metal, on which a precious metal is arranged. There is a risk that such a catalyst, functioning like an SO_x-trap, may increase the pressure drop in the exhaust aftertreatment system. Increased back pressure of the exhausts increases the load on the engine, which in turn results in an increased fuel consumption. US 3,429,656 describes an exhaust treatment system for vehicles, where exhausts that leave the engine are led into a chamber comprising a perforated inner pipe, which distributes the exhausts and leads the exhausts in a radial direction through material that is capable of catching sulphur dioxide from the exhausts. However, this solution also increases the pressure drop of the exhausts in an exhaust aftertreatment system.

In addition to sulphur, other substances that may accumulate in the diesel oxidation catalyst also occur, which may not be removed by way of an increased temperature. It has become apparent that phosphor in particular is problematic in prior art exhaust aftertreatment systems, since compounds containing phosphor poison and/or deactivate the diesel oxidation catalyst. Phosphor is, for example, present in certain fuels such as bio-fuels, or is used as an addition in certain motor oils and may therefore also be present in the exhausts from the combustion engine. Post-mortem analyses of diesel oxidation catalysts, where bio fuels had been used indicate that large amounts of toxins, such as phosphor, had accumulated in the diesel oxidation catalyst.

Poisoning and/or deactivation of the diesel oxidation catalyst leads to a deteriorated efficiency of the diesel oxidation catalyst, and in the longer run it also impacts subsequent components in the exhaust aftertreatment system. Since the different catalysts are often in-built with additional components in a joint unit, i.e. an exhaust aftertreatment device as described above, it is not easy to remove one individual catalyst separately from a vehicle in order to clean, regenerate or replace the same. Replacing the entire exhaust aftertreatment device also entails a significant cost. A replacement of a catalyst, for example a diesel oxidation catalyst, in exhaust aftertreatment devices permitting this, also entails a significant cost since such catalysts are expensive. It is therefore desirable to minimise the poisoning or at least substantially delaying the poisoning of a catalyst, in particular in the catalyst that is arranged first in the direction of the exhaust flow, in the exhaust aftertreatment device.

Apart from this, there are currently also statutory requirements in some states, unions of states or other forms of regions requiring that the exhaust aftertreatment device have a minimum life expressed as a period of time and/or an accumulated driving distance for the vehicle, such as for example 7 years or 700 000 kilometres, without exceeding the emission requirements. This means that an exhaust aftertreatment system for vehicles must be built in such a manner that it either has such a life or may easily be regenerated, so that an exhaust aftertreatment device does not need to be replaced with a new one within the statutory period/driving distance.

SUMMARY OF THE INVENTION

One objective of the present invention is to reduce the risk of, or alternatively delay deactivation of a catalyst, such as a diesel oxidation catalyst, in an exhaust aftertreatment system without substantially impacting the pressure of the exhausts in the exhaust aftertreatment system.

The objective is achieved with an exhaust aftertreatment system in accordance with the independent claim 1. The exemplified embodiments are defined by the non-independent claims.

The exhaust aftertreatment system according to the present invention makes it possible for chemical toxins that may deactivate or poison a catalyst, in particular the catalyst that is arranged first in an exhaust aftertreatment device (such as a diesel oxidation catalyst), inside an exhaust aftertreatment system, to be caught before they reach the catalyst in the exhaust aftertreatment device. In this way, the amount of chemical toxins, which are accumulated in the catalyst, is reduced, and the life of the catalyst, as well as of the entire exhaust aftertreatment device, is drastically extended before it needs to be regenerated or replaced. By arranging an elongated element intended to catch chemical toxins in the exhaust channel, extending between the combustion engine and the exhaust aftertreatment device, the elongated element may easily be removed from the exhaust aftertreatment system in a vehicle, and either be replaced or regenerated, without the exhaust aftertreatment device having to be removed from the vehicle and dismantled. Further, the element does not significantly impact the pressure drop in the exhaust channel, and therefore does not impact the combustion conditions in the engine and it also does not reduce the efficiency of the subsequent exhaust aftertreatment device. In addition, the elongated element creates a better mixing of exhausts and prevents laminar flow in the exhaust channel upstream of the exhaust aftertreatment device. Turbulent flow, and thus improved exhaust mixing, reduces the mass transport and increases the total reaction speed of the exhausts, which results in an improved combustion of residual fuel and reduces formation of soot.

The exhaust aftertreatment system for treatment of exhausts from a combustion engine according to the present invention comprises an exhaust aftertreatment device and an exhaust channel, adapted to be arranged between an exhaust outlet in a combustion engine and an exhaust inlet in the exhaust aftertreatment device. The exhaust aftertreatment device comprises at least one catalyst adapted to purify the exhausts. Preferably, the exhaust aftertreatment device comprises at least one diesel oxidation catalyst, one particulate filter, such as a catalytically coated particulate filter, and a selective catalytic reduction catalyst. Means adapted to catch at least one substance or compound that may deactivate a catalyst in the exhaust aftertreatment device, such as the diesel oxidation catalyst, are arranged in the exhaust channel. Said means constitute an elongated element with a first end and an opposite second end in the element's longitudinal direction, said first and second ends each being arranged to be attached in a wall of the exhaust channel. The elongated element is thus arranged in such a manner that exhausts may flow on all sides thereof, except its first and second end, which are arranged to be attached in the exhaust channel.

A cross sectional area of the elongated element in a radial cross sectional plane of the exhaust channel, in the direction of the flow of the exhausts, suitably occupies less than 10%, preferably less than 5%, of a cross sectional area of the inner volume of the exhaust channel in said radial cross sectional plane of the exhaust channel. This ensures that the elongated element does not impact the pressure of the exhausts in such a manner that the load on the combustion engine or the efficiency of the exhaust aftertreatment device are negatively impacted.

Preferably, the elongated element is arranged in such a way that it not only prevents laminar flow, but also so that it creates increased turbulence in the exhaust flow. This improves the absorption of substances or pollutants that may poison and deactivate the catalyst in the exhaust aftertreatment device.

The elongated element is suitably detachably attached in the exhaust channel, so that it is possible to replace the elongated element when needed, or alternatively to remove it from the exhaust channel in order to clean or regenerate it, and subsequently reinsert it into the exhaust channel. This may be achieved by a wall in the exhaust channel comprising at least one opening through the wall, preferably a substantially radial opening, through which the elongated element may be inserted into or removed from the exhaust channel. Alternatively, the exhaust channel may comprise several exhaust channel sections, where said element is arranged inside a first exhaust channel section, which is detachably arranged in relation to at least one second exhaust channel section, adjacent to said first exhaust channel section.

However, it is also conceivable that the elongated element may not be detachably arranged inside the exhaust channel, but that the entire exhaust channel is released from the exhaust aftertreatment device and from the combustion engine, respectively, to be replaced, regenerated or cleaned.

The longitudinal direction of the elongated element may suitably be arranged substantially in parallel with the radial direction of the exhaust channel, or alternatively be arranged in the exhaust channel's radial direction, in such a manner that the longitudinal element's longitudinal direction is arranged substantially at a right angle in relation to the flow of exhausts through the exhaust channel. That is to say, the elongated element's longitudinal direction may suitably be arranged in a radial cross sectional plane of the exhaust channel, which is at a right angle in relation to the exhaust channel's central axis. Said elongated element may alternatively be arranged so that the element's longitudinal direction is arranged in a plane having a first angle in relation to an axial cross sectional plane of the exhaust channel, and a second angle in relation to a radial cross sectional plane of the exhaust channel, so that each one of said first and second angles is different from 0° and from 90°. Accordingly, the elongated element is arranged so that it is at an angle in relation to the main flow direction of the exhausts along the central shaft of the exhaust channel. In this manner, it is possible to increase the surface area of the elongated element, in order thus to further improve the uptake of substances or compounds from the exhaust gases that constitute chemical toxins for the catalyst.

The elongated element may, for example, be designed as a rod and have a substantially circular, oval or square cross section at a right angle in relation to its longitudinal direction. In this manner, the elongated element does not take up such a large volume in the exhaust channel, and thus does not cause any substantial impact on the pressure of the exhausts in the exhaust channel.

Alternatively, the elongated element may consist of a plate, where the plate has a first extension in the axial plane of the exhaust channel, or in a plane parallel with the exhaust channel's axial plane. The first extension is larger than the element's surface area, t which is arranged to be hit by the exhaust flow first, which means that the first extension is larger than a second extension, which is at a right angle in relation to the plate's longitudinal direction. In this manner, the area of the elongated element may be increased, and thus achieve an increased interception of chemical toxins from the exhausts without, substantially impacting the pressure of the exhausts in the exhaust channel.

According to one embodiment, several elongated elements, which are adapted to catch at least one substance or one compound that may deactivate a catalyst in the exhaust aftertreatment device, are arranged in the exhaust channel at a distance from each other, and after each other in the primary flow direction of exhausts through the exhaust channel from the combustion engine to the exhaust aftertreatment device. In this manner, the interception of chemical toxins from the exhausts is further improved. The several elongated elements with their respective longitudinal directions may, but need not, be rotating in relation to each other with respect to the axial plane of the exhaust channel, and thus further increase the turbulence of the exhausts, so that the interception of chemical toxins from the exhausts is further improved. This means that a first of said several elongated elements is arranged in such a manner that its longitudinal direction is arranged at a first angle in relation to the axial plane of the exhaust channel, and a second of said several elongated elements is arranged in such a manner that its longitudinal direction is arranged at a second angle in relation to the axial plane of the exhaust channel. For example, the longitudinal directions of the various elongated elements may be rotated by 30°, 45° or 60° in relation to each other around to the central axis of the exhaust channel.

Said elongated element may suitably comprise a material adapted to catch phosphor or phosphor containing compounds, since these types of chemical toxins are difficult to remove from an exhaust aftertreatment device with conventional methods to regenerate the different components of the exhaust aftertreatment device.

As described above, the elongated element is preferably arranged in such a way that it causes an increased turbulence of the flow of exhausts in the exhaust channel, wherein it may have a relatively small surface area to catch the chemical toxins in the exhausts, for example compared with prior art honeycomb structures to catch SO_x.

The element may, for example, be coated with prior art materials to catch chemical toxins in an exhaust aftertreatment system. Since the elongated element is relatively small, a smaller amount of catalytic materials is required compared with prior art solutions, so that the element constitutes a cost effective solution to the problem with poisoning and deactivation of a catalyst in an exhaust aftertreatment device.

The present invention also relates to a vehicle comprising a combustion engine and an exhaust aftertreatment system as described above. The vehicle may for example be a truck, a bus or a passenger car. The vehicle may also be a marine vehicle or a terrain vehicle.

DESCRIPTION OF DRAWINGS Fig. la shows a schematic side view of a vehicle comprising a combustion engine and an exhaust aftertreatment device. Fig. lb shows a perspective view of an exhaust aftertreatment system comprising an exhaust aftertreatment device and an exhaust channel.

Fig. lc schematically shows an example of an exhaust aftertreatment device. Fig. 2 illustrates a radial cross sectional view of an exhaust channel in an exhaust

aftertreatment system, in accordance with an exemplifying embodiment of the invention.

Fig. 3 illustrates a radial cross sectional view of an exhaust channel in an exhaust

aftertreatment system, in accordance with another exemplifying embodiment of the invention.

Fig. 4 illustrates a radial cross sectional view of an exhaust channel in an exhaust

Fig. 5 illustrates an axial cross sectional view of an exhaust channel in an exhaust

aftertreatment system, in accordance with another exemplifying embodiment of the invention. Fig. 6 illustrates an axial cross sectional view of an exhaust channel in an exhaust

Fig. 7 illustrates an axial cross sectional view of an exhaust channel in an exhaust

aftertreatment system, in accordance with another exemplifying embodiment of the invention. Fig. 8 illustrates a radial cross sectional view of an exhaust channel in an exhaust aftertreatment system, in accordance with another exemplifying embodiment of the invention. Fig. 9 illustrates a perspective view of a part of an exhaust channel in an exhaust

DETAILED DESCRIPTION

Below, the invention is described in further detail with reference to the enclosed figures. The invention is not limited to the embodiments described and displayed in the figures, but may be modified within the framework of the enclosed claims. Furthermore, the figures should not be deemed drawn to scale, since certain features may be exaggerated in order to further illustrate the invention.

The present invention is intended to overcome the problems caused by chemical toxins in exhausts. Toxins in this context means elements or compounds thereof, which may poison or deactivate at least one catalyst in an exhaust aftertreatment device, in particular a diesel oxidation catalyst in an exhaust aftertreatment device. Such toxins may be present either in gaseous form, in particulate form or in some cases even in liquid form, without departing from the invention. Poisoning of such a catalyst usually takes place through toxins accumulating in the catalyst and leading to a so-called fouling (coating) on the catalytic surfaces of the catalyst. Toxins may also accumulate in the catalyst via selective adsorption on the catalytic surfaces of the catalyst. In this manner, the toxins may finally deactivate the catalyst since the catalytic reaction is prevented or at least significantly deteriorated. Examples of toxins are sulphur, phosphor, zinc, calcium, magnesium or alkali metals, or compounds comprising one or several of these elements. In accordance with the present invention, a means to catch substances or compounds in the exhausts from the combustion engine is arranged in the exhaust channel, arranged between an exhaust outlet in the combustion engine and an inlet of an exhaust aftertreatment device, the latter comprising one or several catalysts arranged for purification of the exhausts. In this manner, said means catches at least one substance or compound that may poison or deactivate the components in the exhaust aftertreatment device, in particular the diesel oxidation catalyst in the exhaust aftertreatment device, in cases where this is arranged first of the catalysts in the exhaust aftertreatment device. The exhaust channel generally constitutes an unused part of an exhaust aftertreatment system and functions primarily as a transport distance for the exhausts, from the combustion engine to the exhaust aftertreatment device. By arranging means to catch one or several substances or compounds that may poison or deactivate the diesel oxidation catalyst in this exhaust channel, the exhaust channel is used efficiently. In addition, the life of the exhaust aftertreatment device in the exhaust

aftertreatment system is prolonged, since it may be used for a longer period of time before the exhaust aftertreatment device needs to be replaced or otherwise regenerated.

Furthermore, the fact that said means is arranged in the exhaust channel instead of in the exhaust aftertreatment device means that said means may easily be replaced, for example at an ordinary service of the vehicle, without the exhaust aftertreatment device as such having to be removed from the vehicle and dismantled. Another advantage of the present invention is that the exhaust aftertreatment device does not need to be rebuilt to facilitate the advantages of the invention, but only the exhaust channel needs to be adapted. In this manner, existing vehicles may also use the advantages of the invention by only replacing the exhaust channel with an exhaust channel adapted to contain means to catch said substances and compounds.

The exhaust channel constitutes a pipe shaped element, which may comprise several bends or similar, and may thus have a central axis that is not straight. The exhaust channel may be divided into several exhaust channel sections. At least one exhaust channel section may be adapted, in a conventional manner, to allow absorption of vibrations in the exhaust channel, in order thus to minimise the mechanical stress on the exhaust channel. The exhaust channel's radial cross sectional plane is at a right angle in relation to the central axis of the exhaust channel. The exhaust channel's axial cross sectional plane is at a right angle in relation to its radial cross sectional plane, where these cut each other, and extends along the central axis. This means that the axial cross sectional plane of the exhaust channel may be bent in accordance with the bends of the central axis. Furthermore, the exhaust channel does not necessarily need to have a rotationally symmetrical design around its central axis, even if this is preferred. The exhaust channel may also have varying inner and outer diameters along its axial extension, if desired.

The exhaust aftertreatment device comprises at least one catalyst intended to purify the exhausts from the combustion engine. Usually, the exhaust aftertreatment device comprises several different catalysts, such as a DOC, SCR, ASC, and/or CSF. It may also comprise other types of filters and/or silencing means. The exhaust aftertreatment device comprises a house, in which the various components thereof are arranged as one joint entity. The house comprises an exhaust inlet connected to the exhaust channel, which extends from the combustion engine to the exhaust aftertreatment device, and an outlet from which purified exhausts may be led further to the surrounding atmosphere. The exhaust aftertreatment device is built in such a manner that exhausts are not permitted to leave the exhaust aftertreatment device otherwise than through the outlet.

In accordance with the present invention, said means to catch one or several substances or compounds that may poison or deactivate a diesel oxidation catalyst consists of at least one elongated element. The element has a first end adapted for attachment to a wall in the exhaust channel, and an opposite second end in the element's longitudinal direction, which end is also adapted for attachment in a wall of the exhaust channel. Thus, the element extends over the exhaust channel in such a manner that the exhausts which flow through the exhaust channel pass the element on its elongated sides.

As opposed to prior art poison traps, such as honeycomb structures to catch sulphur containing compounds, the elongated element is relatively narrow. Thus, there is no substantial impact on the pressure of the exhausts in the exhaust channel, which in turn could impact the load on the combustion engine and/or the efficiency of subsequent components in the exhaust aftertreatment device.

The elongated element may have an extension in the exhaust channel's axial direction, which extension is larger than its extension in the exhaust channel's radial direction at a right angle in relation to the elongated element's longitudinal direction. In this manner, the surface of the elongated element may be increased, without substantially impacting the pressure of the exhausts in the exhaust channel. One example of such an elongated element is an element in the form of a plate or disc, or an elongated element with an oval or rectangular cross section.

By arranging the elongated element so that it extends across, or angularly, in relation to the flow of the exhausts through the exhaust channel, the elongated element will also increase the turbulence of the exhausts. This is an advantage, since it facilitates a larger volume of exhausts will coming into contact with the elongated element, and thus increases the amount of substances or compounds that may be caught up by the elongated element. The elongated element may be made by prior art materials within the technical area, in order to catch the intended substances or compounds consisting of toxins in the exhausts. For example, the elongated element may consist of a load carrier with at least one catalytic coating. Since it has been shown that sulphur containing compounds may be removed from a diesel oxidation catalyst, or from another catalyst in the exhaust aftertreatment device, by temporarily increasing the temperature of the exhausts, the elongated element does not need to be primarily adapted to catch sulphur or sulphur containing compounds. However, it has become apparent that phosphor is a substance difficult to remove from a catalyst, so that it is preferable for the elongated element to at least be adapted to catch phosphor and/or phosphor containing pollutants.

It is preferred for the elongated element to be replaced when needed, or alternatively to be removed from the exhaust aftertreatment system, in such a manner that the elongated element may be regenerated or otherwise cleaned. This may be achieved in various ways. One alternative is to arrange the elongated element in one section of the exhaust channel, which section may be detached from the rest of the exhaust channel for cleaning or regeneration, or which alternatively may be replaced. Another alternative is to arrange the elongated element in such a manner that it may be inserted into the exhaust channel via a through opening, for example a substantially radial through opening in the wall of the exhaust channel, and removed from the exhaust channel through the same. In such a case it is important to ensure that the exhaust channel is completely sealed when the element is inserted, so that exhausts from inside the exhaust channel may not flow out through such opening. Furthermore, it is crucial that the element is fixedly anchored during engine operation, and thus that there is no risk that it may come lose, for example as a consequence of vibrations in the engine, the exhaust channel or the vehicle as such. This may be done in conventional ways, such as by arranging the elongated element against a seat in the exhaust channel, adapted to receive and anchor the elongated element, or by screwing the elongated element to a wall in the exhaust channel with means adapted for this purpose.

Fig. la shows a schematic side view of a vehicle 100 in the form of a truck. The vehicle 100 is equipped with a combustion engine 2 arranged to operate the vehicle's driving wheels 17 via a gearbox and a cardan shaft (not displayed). The combustion engine 2 is operated by a fuel, which is fed to the combustion engine with the help of a fuel system comprising a fuel tank 16. The exhausts from the combustion engine 2 are transported via an exhaust channel 4 to an exhaust aftertreatment device 3.

Fig. lb shows a perspective view of an exhaust aftertreatment system 1 comprising an exhaust aftertreatment device 3 and an exhaust channel 4. The exhaust channel 4 is arranged between an exhaust outlet 5 of a combustion engine 2 (only displayed schematically) and an inlet 6 of the exhaust aftertreatment device 3. The exhaust channel is thus arranged for transport of exhausts from the combustion engine to the exhaust aftertreatment device. Fig. lc schematically shows an exemplified exhaust aftertreatment device 3 comprising a diesel oxidation catalyst (DOC) 7, a selective catalytic reduction catalyst (SCR) 8 arranged downstream of the DOC, and a particulate filter 13 arranged downstream of the SCR-catalyst. The different components of the exhaust aftertreatment device may be arranged in different ways and additional components may be present. For example, the exhaust aftertreatment device may also comprise silencing means, additional particulate filters, and additional catalysts, if desired. Any exhaust aftertreatment device may be used according to the invention, provided that it comprises at least one catalyst. Preferably, the exhaust

aftertreatment device comprises at least one diesel oxidation catalyst and one SCR-catalyst, and potentially a catalytically coated particulate filter, however not necessarily arranged in the order displayed in Fig. lc. Fig. 2 shows a cross sectional view of the exhaust channel 4 across the primary flow direction of the exhausts, i.e. a radial cross sectional view, according to one exemplifying embodiment of the invention. An elongated element 9 is arranged in the exhaust channel [sic:4], in such a manner that a first end 10 of the element, and an opposite second end 11 in the element's longitudinal direction are both attached to the wall 12 of the exhaust channel. In this manner, the elongated element 9 extends across the exhaust channel. The exhausts in the exhaust channel may thus flow around the elongated element along its elongated sides. The elongated element's longitudinal direction is, according to the displayed exemplified embodiment, arranged in the radial cross sectional plane of the exhaust channel. In the illustrated embodiment, the element's longitudinal direction also coincides with the radial direction of the exhaust channel.

Even though it is not displayed in the figure, an attachment of an elongated element in the exhaust channel's wall may suitably be achieved with the help of attaching means, for example in order thus to ensure that there is no risk that the elongated element moves when the exhaust treatment system is in operation.

The elongated element may, for example, be shaped as a rod with a substantially circular, oval, square or rectangular cross section.

Fig. 3 shows a cross sectional view which differs from the embodiment exemplified in Fig. 2 since, in addition to a first elongated element 9a, an additional elongated element 9b is arranged in the exhaust channel 4. Each one of the elongated elements comprises a first end 10a, 10b, and a second end 11a, lib, each of which is attached in the exhaust channel's wall 12. The additional elongated element 9b is arranged at a distance from the first elongated element 9a, in the direction of the flow of the exhausts through the exhaust channel. Further, the additional elongated element 9b is arranged in such a manner that its longitudinal direction is rotated 90° in relation to the first elongated element's 9a longitudinal direction, and thus at least one of the elongated elements is arranged in such a way that its longitudinal direction is rotated in relation to the exhaust channel's axial plane. In this manner, the elongated elements 9a, 9b will contribute to an additional increase of the turbulence of the exhaust flow through the exhaust channel. This means that, compared with the exemplifying embodiment comprising a single elongated element 9, as displayed in Fig. 2, the two elongated elements will, according to the exemplifying embodiment in Fig. 3, jointly achieve a larger surface for catching chemical toxins from the exhausts and also increase the turbulence further, which also contributes to improved interception of chemical toxins from the exhausts.

It is of course possible to arrange more than two elongated elements in the exhaust channel. These may suitably be arranged at a distance from each other, in the direction of the exhaust flow through the exhaust channel. Fig. 4 shows an example of such an exemplifying

embodiment comprising four elongated elements 9a, 9b, 9c, 9d, which are arranged after each other in the direction of the exhaust flow, and arranged in such a manner that their respective longitudinal directions are rotated in relation to each other. It is also possible to arrange the several elongated elements in such a manner that at least two of the elongated elements have longitudinal directions substantially parallel to each other. In accordance with the present invention, the number of elongated elements may be adapted to the desired amount of interception of chemical toxins that is desired to be obtained, but is suitably between one and ten elongated elements. If too many elongated elements are arranged in the exhaust channel, this may impact the pressure of the exhausts, which is not desirable. The number of possible elongated elements depends, however, on their

dimensions, their orientation and placement in the exhaust channel, as well as on the construction and dimension of the exhaust channel, and therefore needs to be determined for each specific case.

The elongated elements may be arranged anywhere along the exhaust channel's axial extension. However, it is preferred for them to be arranged closer to the exhaust

aftertreatment device than to the combustion engine, because of the vibrations that the exhaust channel may be subjected to in the vicinity of the combustion engine.

Fig. 5 shows an axial cross section of a part of the exhaust channel, according to one exemplifying embodiment of the present invention. The primary flow of exhausts F through the exhaust channel is illustrated with an arrow. Several elongated elements 9a, 9b are arranged after each other in the primary direction of the exhaust flow through the exhaust channels, i.e. at a distance from each other along a central axis A of the exhaust channel. A first set of elongated elements 9a is arranged in such a manner that their respective longitudinal directions are substantially parallel with each other, and are rotated 90° in relation to a longitudinal direction of an elongated element 9b in a second set of elongated elements. Fig. 5 thus corresponds to the exemplifying embodiment according to Fig. 3, but with several first elongated elements 9a and several second elongated elements 9b.

Fig. 6 illustrates an axial cross section of the exhaust channel, in accordance with another exemplifying embodiment. In addition to a first elongated element 9, which is arranged so that its longitudinal direction substantially coincides with the radial direction of the exhaust channel, an additional elongated element 9e is arranged in the exhaust channel, in such a manner that its longitudinal direction is arranged in a plane that is angled in a first direction in relation to a radial cross sectional plane of the exhaust channel. A third elongated element 9f is arranged in such a manner that its longitudinal direction is arranged in a plane that is angled in a second direction in relation to a radial cross sectional plane of the exhaust channel. By arranging elongated elements in such a manner that they are angled in relation to a radial direction of the exhaust channel, as displayed in the Figure for the elongated elements 9e and 9f, the surface of the elongated elements may be increased, whereupon they may catch more chemical toxins than one element arranged in such a manner that its longitudinal direction coincides with or is substantially parallel with a radial direction of the exhaust channel. Even though this is not displayed in the figure, naturally the elongated elements that are angled in relation to the radial direction of the exhaust channel may be arranged in such a manner that their respective longitudinal directions are substantially parallel with each other. Furthermore, the exhaust channel does not need to comprise an elongated element, whose longitudinal direction coincides with the exhaust channel's radial direction, but the elongated element need only be arranged in such a manner that its respective ends 10, 11 in the longitudinal direction are attached in the wall of the exhaust channel 12.

Fig. 7 shows an axial cross section in accordance with another exemplifying embodiment. In this case, the elongated element consists of a plate 9g, arranged in such a manner that its longitudinal direction extends substantially in the radial direction of the exhaust channel, and its respective ends 10, 11 are arranged for attachment in the exhaust channel's wall. The plate 9g also has an extension in the exhaust channel's axial direction, which extension is larger than the width of the plate (that is to say a surface which is at a right angle in relation to the longitudinal direction of the element that is in the form of a plate, but which extends substantially in parallel with a radial direction of the exhaust channel). Another elongated element in the form of a plate 9h may be arranged at a distance from the first plate 9g, and rotated in relation to this in such a manner that the plates' respective longitudinal directions are at 90° in relation to each other.

Fig. 8 illustrates a radial cross section of the exhaust channel in accordance with another exemplifying embodiment. In accordance with this, two elongated elements 9i, 9j are arranged in the exhaust channel in such a manner that their respective longitudinal directions are substantially parallel with each other, and parallel with a radius of the exhaust channel. In this case, the elongated elements are arranged at the same axial position in the exhaust channel's axial direction. However, it is also conceivable for the two elements to be arranged at a distance from each other in the direction of the flow, i.e. in the exhaust channel's axial extension, if desired.

Fig. 9 illustrates a perspective view of a part of an exhaust channel, in accordance with another exemplifying embodiment. Three elongated elements 9 are displayed, whose respective longitudinal directions are rotated in relation to each other, around the exhaust channel's central axis A. The elongated elements are arranged at a distance from each other along the central axis of the exhaust channel, i.e. in the primary direction of the exhaust flow through the exhaust channel. Furthermore, the elongated elements in the embodiment displayed have a substantially oval cross section in relation to the longitudinal axis of the respective elements 9, and are arranged in such a manner that their extension in the exhaust channel's axial direction is greater than their extension in the radial direction of the exhaust channel, at a right angle in relation to the respective elongated elements' longitudinal shaft. As displayed in the figure, the exhaust channel has several openings 14 in the wall 12 of the exhaust channel, through which openings the elongated elements may be inserted into and removed from, respectively, the exhaust channel. The elongated elements are detachably arranged in the exhaust channel and attached therein with suitable means for this purpose (not displayed). As specified above, the invention is not limited to the embodiments displayed in the figures and described above. Each one of the elongated elements 9 and 9a-9j described above may be combined with each other in any combination, if desired.

In each one of the examples described above, a longitudinal direction of the elongated element relates to an extension, specifically a central axis, of the elongated element, which axis is substantially parallel with a surface of the elongated element intended to be hit by the flow of exhausts through the exhaust channel. Furthermore, the vehicle according to the invention is not limited to a truck, as displayed in Fig. la, since the vehicle may be any vehicle comprising a combustion engine and an exhaust aftertreatment system as described above.

Claims

Exhaust aftertreatment system (1) for treatment of exhausts from a combustion engine

(2), said exhaust aftertreatment system comprising an exhaust

aftertreatment device

(3) and an exhaust channel

(4), arranged between an exhaust outlet

(5) in a combustion engine and an exhaust inlet (6) in the exhaust

aftertreatment device, wherein the exhaust aftertreatment device comprises at least one catalyst adapted to purify the exhausts, characterised in that a means adapted to catch at least one substance or compound that may deactivate the at least one catalyst in the exhaust aftertreatment device is arranged in the exhaust channel, wherein said means consist of an elongated element (9, 9a-9j) with a first end (10) and an opposite end (11) in the element's longitudinal direction, said first and second end each arranged to be attached in a wall (12) in the exhaust channel.

Exhaust aftertreatment system according to claim 1, wherein a cross sectional area of said element (9, 9a-9j) in a radial cross sectional plane of the exhaust channel (4) occupies less than 10%, preferably less than 5%, of a cross sectional area of the inner volume of the exhaust channel in said radial cross sectional plane of the exhaust channel.

Exhaust aftertreatment system according to claim 1 or 2, wherein said elements (9, 9a-9j) are arranged in such a way that it creates increased turbulence in the exhaust flow.

Exhaust aftertreatment system according to any of the previous claims, wherein said element (9, 9a-9j) is detachably attached in the exhaust channel (4).

Exhaust aftertreatment system according to claim 4, wherein a wall (12) in the exhaust channel comprises at least one through opening (14) through the wall, through which the elongated element (9, 9a-9j) may be inserted into, and removed from, respectively, the exhaust channel.

6. Exhaust aftertreatment system according to any of claims 1-4, wherein the exhaust channel (4) comprises several exhaust channel sections, the elongated element (9, 9a-9j) is arranged inside a first exhaust channel section, which is detachably arranged in relation to at least one second exhaust channel section, adjacent to said first exhaust channel section.

7. Exhaust aftertreatment system according to any of the previous claims, wherein the elongated element's longitudinal direction is arranged substantially in parallel with the exhaust channel's radial direction, or alternatively is arranged in the exhaust channel's radial direction.

8. Exhaust aftertreatment system according to any of claims 1-6, wherein the

elongated element (9e, 9f) is arranged in the exhaust channel (4) in such a manner that the element's longitudinal direction is arranged in a plane having a first angle in relation to an axial cross sectional plane of the exhaust channel, and a second angle in relation to a radial cross sectional plane of the exhaust channel, so that each one of said first and second angles is different from 0° and from 90°.

9. Exhaust aftertreatment system according to any of the previous claims, wherein said element has a substantially circular, oval or square cross section.

10. Exhaust aftertreatment system according to any of claims 1-8, wherein the

elongated element (9g, 9h) consists of a plate, wherein the plate has a first extension in the exhaust channel's axial plane, or in a plane with is parallel with the exhaust channel's axial plane, which extension is larger than a second extension of the plate, which second extension is at a right angle in relation to the plate's direction.

11. Exhaust aftertreatment system according to any of the previous claims, wherein several elongated elements (9, 9a-9j), which are adapted to catch at least one substance or one compound that may deactivate a catalyst in the exhaust aftertreatment device, are arranged in the exhaust channel at a distance from each other, in the primary flow direction of exhausts through the exhaust channel, from the combustion engine to the exhaust aftertreatment device.

12. Exhaust aftertreatment system according to claim 11, wherein a first of said several elongated elements (9, 9a-9j) is arranged in such a manner that its longitudinal direction is arranged at a first angle in relation to the axial plane of the exhaust channel, and a second of said several elongated elements is arranged in such a manner that its longitudinal direction is arranged at a second angle in relation to the axial plane of the exhaust channel.

13. Exhaust aftertreatment system according to any of the previous claims, wherein said element (9, 9a-9j) comprises a material adapted to catch phosphor or phosphor containing compounds.

14. Vehicle (100) comprising a combustion engine (2) and an exhaust aftertreatment system (1) according to one of the previous claims, said exhaust aftertreatment system being adapted for aftertreatment of exhausts from the combustion engine.

15. Vehicle according to claim 14, wherein the motor vehicle is a truck, a bus or a car.