DE10216272A1 - Exhaust gas treatment arrangement for an internal combustion engine - Google Patents

Abstract

An exhaust gas treatment arrangement for an internal combustion engine with at least one exhaust gas discharge opening 9 is proposed, which has a plurality of exhaust gas catalytic converters 29 close to the internal combustion engine, each of which comprises at least one cylindrical catalyst carrier body 42, a pipe flange 17 for direct coupling to the exhaust gas discharge opening 9 and a catalyst holder pipe 27 coupled to the pipe flange 17 which has a first tube region 31, in which the catalyst carrier body 42 is received, and a second tube region 39 adjoining the first tube region 31 for removing exhaust gas treated in the catalyst carrier body 42. The exhaust gas treatment arrangement is characterized in that the first tube region 31 has a larger inner diameter D1 than the second tube region 39. The catalyst carrier body 42 is supported with respect to the first tube region 31 by means of sleeves 47 and / or wire mesh sleeves 59.

Description

The present invention relates to a Exhaust gas treatment arrangement with at least one exhaust gas catalyst for treatment of exhaust gases from an internal combustion engine with at least one Exhaust gas discharge port.

To reduce pollutants in exhaust gases Internal combustion engines are catalytic converters in the exhaust system Internal combustion engine arranged. The exhaust line includes at least a group of several directly to the Exhaust ports connected especially as an exhaust manifold designated pipe sections, which by the Pick up exhaust gases emitted. To these pieces of pipe pipe junctions are coupled to the exhaust gases from the multiple exhaust ports of a group of Collect exhaust ports in a single pipe to which a silencer is connected, from which the exhaust gas is finally released to the environment. Before entering The exhaust gas passes through the silencer Exhaust gas catalytic converter, in which pollutants contained in the exhaust gas, such as for example carbon monoxide and nitrogen oxides in less harmful products are converted. In motor vehicles the catalytic converter usually together with the silencer on Vehicle floor of the motor vehicle arranged.

For efficient treatment of the exhaust gas, the Exhaust gas catalyst an increased operating temperature of z. B. above 600 ° C exhibit. When the engine starts cold, there is one certain period of time necessary until the catalytic converter its intended operating temperature reached, during which time then optimal treatment of the exhaust gases is not possible and accordingly increased amounts of pollutants to the environment be delivered. This time period is one on the vehicle floor arranged catalytic converter, among other things, therefore comparatively long because the catalytic converter with a relative large distance from the internal combustion engine is arranged and the exhaust gases when they enter the catalytic converter due to the heat exchange with that between the internal combustion engine and catalytic converter provided pipe connections in the Comparison to exit directly from the internal combustion engine have cooled down greatly.

Therefore, catalytic converters have been developed that are closer to the internal combustion engine, for example in the exhaust manifold, are arranged and which accordingly after a cold start reach their intended operating temperature faster, which itself can be even higher than that of comparable Exhaust gas catalysts in the area of the vehicle floor are arranged.

Such close to the exhaust port of the Internal combustion engine arranged catalytic converter is from US 6,062,020 known. This catalytic converter has one Catalyst carrier body of frustoconical shape, which in a conically tapered exhaust pipe is inserted. The The catalyst carrier body is conical compared to that tapered tube supported by a fiber mat. The Fiber mat has a certain elasticity, which the sensitive catalyst carrier body in front of the close to the Protects strong vibrations occurring internal combustion engine.

This mounting concept for the catalyst carrier body is however perceived as disadvantageous because proper mounting of the catalyst carrier body with a relatively precise to adjust the axial pressure in the conical tapered pipe section must be pressed. Further this bracket concept excludes the use of cylindrical catalyst carrier bodies, which with regard to a flow through it would be advantageous.

Accordingly, an object of the present invention is a Propose exhaust gas treatment arrangement with which especially cylindrical catalyst carrier body close to the Internal combustion engine can be arranged.

In a first aspect, the invention is based on one Exhaust gas treatment arrangement for an internal combustion engine at least one exhaust gas discharge opening, wherein several Catalytic converters are provided, and each being Exhaust gas catalytic converter of a separate exhaust gas discharge opening of the Internal combustion engine is assigned. The catalytic converter comprises one Catalyst carrier body, which has a surface on which the catalyst material is provided, which is the chemical reaction to transform the harmful Promotes combustion products into less harmful products. In particular, the catalyst carrier body in its Inside a variety of flow channels ready Are provided on the inside surface with the catalyst material. The Flow channels are preferably channels from along their length is substantially uniform in cross section a flow through the exhaust gas catalyst as possible to allow low flow losses. Accordingly, the Catalyst carrier body is essentially cylindrical Shape, with the cylindrical shape not necessarily the Must have the shape of a circular cylinder. Rather are Cylinder shapes are provided with any footprint, such as hexagonal or square base.

The catalyst carrier body is in a catalyst holder tube added, which indirectly to the exhaust gas outlet of the Internal combustion engine is coupled. Preferably that is However, catalyst support tube directly, i.e. H. without inserting further separate pipe sections to the exhaust gas discharge opening coupled.

The invention is characterized in that the Catalytic converter holding pipe two pipe sections in a row having, wherein the catalyst carrier body, seen in Flow direction of the exhaust gas, in a front first Pipe area is included, which is a larger Has inner diameter as a the first tube area in Direction of flow of the exhaust gas subsequent second pipe area.

This interpretation is based on the consideration that of the Total cross section of the catalyst carrier body only one Part available as a flow cross-section for the exhaust gas stands. With a view to reducing flow losses in the catalyst carrier body, its cross section is in Compared to the cross section of the second pipe area increased.

In particular, it is provided that the cross section of the Exhaust gas catalyst carrier body is equal to or larger than that Inner diameter of the second pipe area.

With a view to simple manufacture of the Catalyst holder tube is preferably made of a single Pipe piece integrally formed. This means that the first and the second pipe area not by separate pipe sections are provided, which by connection techniques such for example welding or screwing together are.

The invention provides a second aspect arrangement of exhaust gas catalysts close to the engine, wherein each catalytic converter has a plurality of exhaust gas discharge openings is assigned to the internal combustion engine, although not a single catalytic converter all Exhaust ports are assigned. Accordingly, there are several Exhaust gas catalysts are provided, each in a separate Catalyst holding tube is added. Accordingly, in Flow direction upstream of the catalytic converter Pipe branching provided around each catalyst support pipe couple multiple exhaust ports. Furthermore, in Flow direction behind the several catalytic converters Pipe junction provided to the several Catalyst holder pipes to a single exhaust pipe merge.

Preferably, as a transition between the first and the inserted into the second pipe section, a third pipe section, whose inside diameter is smaller than that of the first Pipe area and is larger than that of the second pipe area. This third pipe section preferably represents one Radial shoulder ready on which the catalyst carrier body itself or with the interposition of another holding structure is axially supported so that it slips in fixed in an axial direction towards the second tube region is.

In contrast to the short, for example on the vehicle floor The catalytic converter in front of the silencer is the close to the internal combustion engine in question Exhaust gas catalytic converter special mechanical and thermal loads and exposed in particular to increased flow pulsations. On is such an exhaust gas catalytic converter near the engine preferably less than 1 m, in particular less than 0.5 m and in particular less than 0.25 m from the internal combustion engine remotely arranged, this length is not on a geometric distance between the catalyst carrier body and relates to the internal combustion engine, but to a length the pipe connection between the catalyst carrier body and Exhaust gas discharge opening of the internal combustion engine.

The catalyst carrier body is preferably through the Pipe flange inserted into the catalyst holder tube, and more preferably such that the catalyst carrier body with its entire length in the first tube area is included.

The catalyst carrier body can, for example, by a ceramic structure, a metallic structure or even a other structure can be formed, but due to the im With regard to the largest possible catalyst surface large number of flow channels mechanically fragile and is sensitive to deformations and breaks. Therefore it is preferred that the catalyst carrier body itself is not in direct contact with the catalyst holder tube, but rather at a distance from an inner jacket of the first Pipe area is arranged. Accordingly, between the Catalyst carrier body and the inner shell of the first Pipe area holding structures for holding the Catalyst carrier body provided to this in the first tube area to fix it sufficiently mechanically and at the same time Transmission of vibrations from the catalyst support tube to dampen the catalyst carrier body.

Such holding structures are preferred, as seen in FIG Flow direction of the exhaust gas, at a front end region and a rear end portion of the catalyst carrier body intended. Are preferably between the front and rear end area axial areas on the Catalyst carrier body provided, which is not by interposed Structures are supported on the catalyst support tube so that these areas also heat transfer from the Catalyst carrier body is reduced to the catalyst holding tube, what with a view to reaching the Operating temperature of the catalyst is advantageous. Then there are direct only at the front and rear end portions Thermal bridges between the catalyst carrier body and the Catalyst support tube formed by the support structures.

Such a support structure is preferably a Spacer sleeve formed, which in particular in the circumferential direction is designed to flow around the To block the catalytic converter through the exhaust gases.

With regard to a damping from on The spacer sleeve has a vibration transmitted to the catalyst carrier body Spring action by being in an area both in Extends axially as well as in the radial direction.

The spacer sleeve is preferably frictionally on the Inner jacket of the first pipe area. Alternatively or in addition to this, however, on the inner jacket of the first Pipe area a circumferential groove can be provided, in which the Spacer snaps in particular when the Exhaust gas catalyst is introduced into the first pipe area. alternative or in addition to this, it is also provided that Spacer sleeve with the inner jacket of the first tube area weld or solder or otherwise joining technology.

As an alternative or in addition, a holding structure can also be used one between the catalyst carrier body and the inner jacket inserted cuff of the first tube area, which as a braid or knitted fabric or fleece or woven fabric or felt made of wire or other material.

A holder in which the Support structure of the front end area by a Spacer sleeve and the holding structure at the rear end area of the Catalyst carrier body through a wire mesh sleeve is formed. This makes it easier to insert the Catalyst carrier body in the first tube area, preferably the spacer sleeve close to the pipe flange with the Catalyst holder tube can be welded.

It is also provided that radially between one in the first tube area supporting area of the spacer sleeve and the catalyst carrier body a cuff of this type is inserted as it was previously as immediately between the first tube area and the catalyst carrier body inserted cuff has been described.

Embodiments of the invention are described below with reference to Drawings explained in more detail. Here shows:

Fig. 1 is a schematic representation of a first embodiment of an exhaust gas treatment apparatus of the invention,

FIG. 2 shows a detailed view in axial longitudinal section of the exhaust gas treatment arrangement shown in FIG. 1,

FIGS. 3 to 7 are detail views on the type of Fig. 2 of further embodiments of the exhaust treatment device according to the invention,

Fig. 8 is a schematic representation of yet another embodiment of the exhaust treatment device,

Fig. 9, yet another embodiment of the exhaust treatment device and

FIG. 10 shows a detailed view of the exhaust gas treatment arrangement shown in FIG. 9.

An exhaust gas treatment arrangement 1 is shown schematically in FIG. 1. This serves to treat exhaust gases from a four-cylinder, four-stroke internal combustion engine 3 with a cylinder head 5 . Fresh air is supplied to the cylinders of the internal combustion engine 3 via intake manifolds connected to the cylinder head, and the exhaust gas produced in the cylinders during combustion is expelled from exhaust gas discharge openings 9 provided on the cylinder head 5 .

The combustion exhaust gases discharged through the exhaust gas discharge openings 9 are discharged to the environment from an exhaust system 11 , which includes the exhaust gas treatment arrangement 1 , via an exhaust end 13 . The exhaust system 11 comprises four exhaust manifold pipes 15 , each of which is screwed to a pipe flange 17 with an exhaust gas outlet opening 9 . The four exhaust manifold pipes 15 are connected to one another at their ends opposite the pipe flanges 17 via a pipe junction 19 in order to combine the exhaust gases expelled from the four cylinders in a manifold 21 which is screwed to the pipe junction 19 via a flange connection 23 . The exhaust manifold 21 leads the exhaust gases through a silencer 25 to the exhaust end 13 .

Pipe areas of the exhaust manifold pipes 15 adjoining the pipe flanges 17 are designed as catalyst holder pipes 27 , each of which receives an exhaust gas catalytic converter 29 in its interior. The combustion exhaust gases pass through the exhaust gas catalysts, which convert harmful combustion products contained in the exhaust gases into less harmful products. In particular, nitrogen oxides are reduced to nitrogen, carbon monoxide is oxidized to carbon dioxide and hydrocarbons are oxidized to carbon dioxide and water.

In FIG. 2, the arrangement of the catalyst 29 is shown in the catalyst holding tube 27 in detail. The catalyst holder tube 27 has a first tube region 31 provided with the flange 17 , the flange 17 being fixedly connected to the cylinder head 5 with screws 35 with the interposition of a seal 33 . The exhaust gas catalytic converter 29 is accommodated within the first tube region 31 . In an exhaust gas flow direction 37 behind the first pipe area 31 , the exhaust gas holding pipe 27 merges into a second pipe area 39 , which leads the exhaust gases to the pipe junction 19 after flowing through the exhaust gas catalytic converter 29 . The first tube region 31 has a larger inner diameter D1 than the second tube region 39 , which has an inner diameter D2. This catalyst holding tube 27 is formed in one piece with its two pipe portions 31, 39, wherein a taper pipe 41 is provided as a transition between the two tube portions 31,. 39

The exhaust gas catalytic converter 29 comprises a catalyst carrier body 42 which is designed as a honeycomb body and has in its interior a multiplicity of schematically illustrated flow channels 43 , the surfaces of which are covered with catalyst material, such as platinum and palladium. The flow channels 43 have essentially the same cross section along their length, so that the entire catalyst carrier body 42 has a cylindrical shape, the cross section of which is circular in the embodiment described in FIG. 2. The catalyst carrier body 42 has a jacket 45 on its outer circumference. The catalyst carrier body 42 is formed from a ceramic material, and the outer surface 45 of the jacket 45 is provided with a metal layer which is firmly connected to a metal sleeve 47 by joining technology. The sleeve 47 holds the catalytic converter 29 within the first pipe region 31 in such a way that the jacket 45 is arranged at a distance A from the catalytic converter holding pipe 27 . The sleeve 47 has the shape of an elongated S in cross section, with an area 49 connected to the jacket 45 of the catalyst carrier body 42 and an area 51 of the sleeve 47 bearing against the inner wall of the first tube area 31 parallel to an axis 53 of the cylindrical catalyst carrier body 42 extend. Between the regions 49 and 51 , a central region 55 of the sleeve 47 extends radially outwards from the region 49 to the flange 17 . The area 51 of the sleeve 47 which bears against the inner jacket of the first tube area 31 is welded to the catalyst holder tube 27 , a weld seam 57 being indicated symbolically in FIG. 2.

At one end of the catalyst carrier body 42 facing away from the flange 17, a wire mesh sleeve 59 is inserted between its jacket 45 and the inner wall of the first tube region 31 , which supports the catalyst carrier body 42 radially with respect to the catalyst holding tube.

To assemble the exhaust gas catalytic converter 29 in the catalyst holding tube 27 , the sleeve 59 is first pulled tightly over one end of the catalyst carrier body 42 , then the catalyst carrier body is first inserted with the sleeve 59 into the opening of the first tube region 31 and pushed so far that the catalyst carrier body 42 is completely accommodated in the first tube region 31 and a distance B between an end face of the catalyst carrier body 42 and the tube flange 17 is approximately 5 mm. The weld seam 57 is then produced between the catalyst holder tube 27 and the region 51 of the sleeve 47 either over the entire circumference or only on a partial circumference, for example by spot welding. Thus, the catalyst carrier body 42 is defined by the sleeve 47 in the axial direction in the catalyst holding tube and supported by both the sleeve and through the sleeve 59 in the radial direction relative to the catalyst holding tube 27th

Variants of the embodiment explained with reference to FIGS. 1 and 2 are shown below. Components which correspond to components of FIGS. 1 and 2 in terms of their structure and function are designated with the same reference numerals as in FIGS . 1 and 2, but are provided with an additional letter to distinguish them. Here, reference is made to the entire preceding description.

An exhaust gas catalytic converter 29 a shown in FIG. 3 in an axial longitudinal section has a structure similar to that of the exhaust gas catalytic converter explained in FIGS . 1 and 2. In contrast to this, however, a catalyst carrier body 42 a is held both at its front and at its rear end by a sleeve 47 a in a first tube region 31 a of a catalyst holder tube 27 a. The two sleeves 47 a each have an S-shaped shape, both of which, starting from area 49 a attached to an outer jacket 45 a of a catalyst carrier body 42 a, extend radially outward over an intermediate area 55 a and towards a pipe flange 17 a and with an end region 51 a frictionally abut an inner wall of the first tube region 31 a.

The catalyst holder tube is in turn formed in one piece, the first tube region 31 a having an inner diameter D1 which is substantially larger than an inner diameter D2 of a tube region 39 a adjoining the first tube region 31 a for removing the exhaust gases. Here, the first pipe portion 31 a opposite to the second tube portion 39 is a so extends that which has in the first pipe portion 31 a recorded catalyst carrier body 42 a has a cross-sectional diameter D3 which is larger than the inner diameter D2 of the second tube portion 39 a.

An embodiment of the exhaust gas treatment arrangement shown in FIG. 4 is constructed similarly to the arrangement shown in FIG. 2. In contrast to this, an end of a catalyst carrier body 42 b facing away from a tube flange 17 b is not supported by a wire mesh sleeve relative to a catalyst holder tube 27 b, but by a further sheet metal sleeve 47 b, which has an area 49 b fixed to the catalyst carrier body 42 b, one after the other radially outside and away from the tube flange 17 b extending central region 55 b and a region 51 b frictionally abutting a first tube region 31 b of the catalyst holder tube 27 b. In order to facilitate insertion of the sleeve 47 b and thus of the catalyst carrier body 42 b into the first tube region 31 b through an opening of the flange 17 b, the sleeve 47 b extends beyond the region 51 b which is in contact with the catalyst tube 27 b with an end region 65 radially inward again.

An embodiment of the exhaust gas treatment arrangement shown in FIG. 5 has a structure similar to that of the exhaust gas treatment arrangement shown in FIG. 3. A catalyst carrier body 42 c is in turn supported at its two axial ends by sheet metal sleeves 47 c with respect to a catalyst holder tube 27 c. However, a pipe flange 17 c of the catalyst holding tube 27 c facing metal sleeve 47 c with an inner wall of a first tube portion 31 c of the catalyst holding tube 27 c abutting portion 51 c with the catalyst holding tube 47 c by a weld 57 c firmly connected. The other metal sleeve 47 c rests with an area 51 c on an inner wall of the first tube area 31 c in a friction-locking manner. Between the area 51 c of this metal sleeve 47 c and an outer jacket 45 c of a catalyst carrier body 42 c, a wire mesh sleeve 59 c is inserted, which is intended to dampen vibrations of the catalyst carrier body 42 c within the catalyst holder tube 27 c.

A further embodiment of the exhaust gas treatment arrangement shown in FIG. 6 has a structure similar to that of the exhaust gas treatment arrangement explained with reference to FIG. 5. In contrast to this, however, a metal sleeve 47 d facing a pipe flange 17 d for supporting a catalyst carrier body 42 d is not welded to a catalyst holder tube 27 d, but is only inserted into it in a frictional manner. For further vibration damping, a metal braided sleeve 59 d is inserted in the two metal sleeves 47 d between their areas 51 d of the metal sleeves 47 d, which are in contact with a first tube area 31 d of the catalyst holding tube 27 d, and an outer jacket 45 d of the catalyst carrier body 42 d.

Furthermore, the first tube region 31 d with an inner diameter D1 does not directly transition into a second tube region 39 d with an inner diameter D2. Rather, between the two tube portions 31 d, 39 d, a third pipe portion 67 with an inner diameter D4 provided which is smaller than the inner diameter D1 and larger than the inner diameter D2. A stop shoulder is formed on a taper 69 between the first tube region 31 d and the third tube region 67 , on which the sheet metal sleeve 47 d facing away from the tube flange 17 d comes to rest in order to prevent the catalyst carrier body 42 from slipping into the catalyst holder tube 27 d ,

An embodiment of the exhaust gas treatment arrangement shown in FIG. 7 has a structure similar to that of the embodiment explained with reference to FIG. 6. In contrast to this, a first tube region 31 e of a catalyst holder tube 27 e has a circumferential groove 71 , in which a sheet metal sleeve 47 e for supporting a catalyst carrier body 42 e with respect to the first tube region 31 e is engaged with a region 51 e, both around the catalyst carrier body 42 e in the direction into the catalyst holder tube 27 e and axially in the opposite direction.

An exhaust gas treatment arrangement 1 f shown in FIG. 8 has a structure similar to that of the exhaust gas treatment arrangement explained with reference to FIGS. 1 and 2. In contrast to this, however, a front end face of catalyst carrier bodies 42 f is not arranged essentially directly at exhaust gas outlet openings 9 f. Rather, these end faces are at a distance B of approximately 20 cm from the exhaust gas discharge openings.

An exhaust gas treatment arrangement 1 g shown schematically in FIG. 9 has a structure that is similar to the exhaust gas treatment arrangement shown in FIG. 8. Here, too, front end faces of exhaust gas catalysts 29 g are arranged with an enlarged distance B of approximately 30 cm from exhaust gas discharge openings 9 g of a cylinder head 5 g. However, each exhaust gas catalytic converter 29 g is not separately assigned to a single exhaust gas discharge opening 9 g. Rather, each exhaust gas catalytic converter 29 g is assigned to a group of two exhaust gas discharge openings 9 g. Here, a pipe junction 75 is arranged between a first pipe region of a catalyst holder tube 27 g, in which the exhaust gas catalytic converter 29 g is received, and pipe flanges 17 g, which are screwed to the exhaust gas discharge openings 9 g, in order to remove the exhaust gases from two exhaust gas discharge openings 9 g of an exhaust gas catalytic converter 29 g feed.

The first pipe areas 31 g, in which the exhaust gas catalysts 29 g are received, are followed by second pipe areas 39 g of the catalyst holding tube 27 g, which open into a further pipe junction 19 g in order to combine the exhaust gases of all four cylinders of the engine 5 g Merge collector tube 21 g.

As shown in FIG. 10, the first tube area 31 g and the second tube area 39 g are in turn made from a single piece of tube. The tube junction 75 is welded to the first tube area 31 g with a weld seam 77 , which was produced after the catalyst carrier body 42 g was inserted into the first tube area.

In the above-described embodiments, the Catalyst carrier body a ceramic Catalyst carrier body, which is metallized on its outer jacket in order attached to it a metal sleeve to support the Fasten the catalyst carrier body metallurgically in the catalyst holder tube to be able to. However, it is also envisaged that Not to manufacture the catalyst carrier body from a ceramic material, but from a metal material, then the attachment the metal sleeve is simplified.

In the previously described embodiments also used a wire mesh sleeve to the Vibration-damping catalyst carrier body compared to Support the catalyst holder tube. This function is different but not limited to a wire mesh sleeve. Rather, other cuffs can be provided, such as for example knitted fabrics or woven fabrics made of wires, ribbons, etc., which do not necessarily have to be made of metal and may include mineral fibers or the like.

In the above-described embodiments in each case in the first region of the catalyst holding tube a single catalyst carrier body arranged. It is however also possible, several in the first tube area Arrange catalyst carrier body, in particular axially one after the other.

Claims (21)

An exhaust gas treatment arrangement for an internal combustion engine ( 39 ) with a plurality of exhaust gas discharge openings ( 9 g), comprising:
a plurality of exhaust gas catalysts ( 29 g) close to the internal combustion engine, each of which comprises at least one cylindrical catalyst carrier body ( 42 g),
a plurality of groups of in each case a plurality of pipe flanges ( 17 g), each pipe flange ( 17 g) being provided for direct coupling to one of the plurality of exhaust gas discharge openings ( 9 g), and
a plurality of catalyst holder tubes ( 27 g), each with a first tube area ( 31 g), in which at least one catalyst carrier body ( 42 g) is accommodated, each of the catalyst holder tubes ( 27 g) being connected to the tube flanges ( 75 ) via a tube branch ( 75 ) 17 g) a group of pipe flanges is coupled. 2. The exhaust gas treatment arrangement as claimed in claim 1, the catalyst holding tube ( 27 g) further comprising a second tube region ( 39 g) adjoining the first tube region ( 31 g) for discharging exhaust gas treated in the catalyst carrier body ( 42 g), and wherein the first tube region ( 31 g) has a larger inner diameter (D1) than the second tube area ( 39 g). 3. An exhaust gas treatment arrangement for an internal combustion engine ( 3 ) with at least one exhaust gas discharge opening ( 9 ), comprising:
a plurality of exhaust gas catalytic converters ( 29 ) close to the internal combustion engine, each of which comprises at least one cylindrical catalyst carrier body ( 42 ),
a plurality of pipe flanges ( 17 ) for direct coupling to an exhaust gas outlet opening ( 9 ) and
a catalyst holding tube ( 27 ) coupled to the tube flange ( 17 ), which has a first tube area ( 31 ) in which the catalyst carrier body ( 42 ) is accommodated, and a second tube area ( 39 ) adjoining the first tube area ( 31 ) for removing in has treated exhaust gas from the catalyst carrier body ( 42 ),
characterized in that the first tube region ( 31 ) has a larger cross section (D1) than the second tube region ( 39 ). 4. Exhaust treatment arrangement according to claim 2 or 3, wherein a cross section (D3) of the catalyst carrier body ( 42 a) is equal to or larger than the cross section (D2) of the second tube region ( 39 a). 5. The exhaust gas treatment arrangement according to one of claims 2 to 4, wherein the first and the second tube region ( 31 , 39 ) of the catalyst holder tube ( 27 ) are integrally formed from a single tube piece. 6. Exhaust gas treatment arrangement according to one of claims 2 to 5, wherein between the first and the second tube region ( 31 d, 39 d), a third tube region ( 67 ) of the catalyst holding tube ( 27 d) is arranged, wherein an inner diameter (D4) of the third tube region ( 67 ) is larger than that of the first pipe section ( 31 d) and smaller than that of the second pipe section ( 39 d). 7. The exhaust gas treatment arrangement according to claim 6, wherein a radial shoulder ( 69 ) is provided on the catalyst holding tube ( 27 d) between the first and the third tube region ( 31 d, 67 ), in order to support the exhaust gas catalyst carrier body ( 42 d) in an axial direction ( 37 d) to fix. 8. Exhaust gas treatment arrangement according to one of claims 1 to 7, wherein a distance (B) between the tube flange ( 17 ) and the catalyst carrier body ( 42 ) is less than 1 m, in particular less than 0.5 m and in particular less than 0.25 m , 9. Exhaust treatment arrangement according to one of claims 1 to 8, wherein the catalyst carrier body ( 42 ) receiving the first tube region ( 31 ) is formed by a one-piece tube and the catalyst carrier body ( 42 ) is received therein with essentially its entire axial length. 10. The exhaust gas treatment arrangement according to claim 9, wherein an outer jacket ( 45 ) of the exhaust gas catalyst carrier body ( 42 ) is arranged at a distance (A) from an inner jacket of the first tube region ( 31 ). 11. The exhaust gas treatment arrangement according to claim 9 or 10 or the preamble of claim 3, wherein the catalyst carrier body ( 42 ) has an axially front end region facing the pipe flange ( 17 ) and an axially rear end region facing away from the pipe flange ( 17 ) and at least on the front and rear end regions is supported radially with respect to the first tube region ( 31 ). 12. The exhaust gas treatment arrangement according to claim 11, wherein a spacer sleeve ( 47 ) is provided in the front and / or rear end region, which is fixed on the one hand to the catalyst carrier body ( 42 ) and on the other hand is supported radially with respect to the first tube region ( 31 ). 13. Exhaust gas treatment arrangement according to claim 12, wherein, seen in the axial longitudinal section, the spacer sleeve ( 47 ) starting from a region ( 49 ) fixed on the catalyst carrier body ( 42 ) in the axial direction and radially outward to a support on the first tube region ( 31 ) Area ( 51 ) extends. 14. The exhaust gas treatment arrangement according to claim 13, wherein the spacer sleeve ( 47 b) extends in the axial direction beyond the supporting region ( 51 b) and radially inward. 15. Exhaust gas treatment arrangement according to claim 13 or 14, wherein a spacer sleeve ( 47 a) is fixed both on the front and on the rear end region, wherein both spacer sleeves ( 47 a) extend in a common axial direction from their on the catalyst carrier body ( 42 a) defined area ( 49 a) extend to the area ( 51 a) supporting on the first tube area ( 31 a). 16. Exhaust gas treatment arrangement according to one of claims 12 to 15, wherein an inner jacket of the first tube region ( 31 e) has a circumferential groove ( 71 ) and the spacer sleeve ( 47 e) is in engagement with the circumferential groove ( 71 ) and in particular is engaged therein. 17. Exhaust gas treatment arrangement according to one of claims 12 to 16, wherein the spacer sleeve ( 47 a) rests frictionally on the inner jacket of the first tube region ( 31 a). 18. Exhaust gas treatment arrangement according to one of claims 12 to 16, wherein the spacer sleeve ( 47 ) is welded or soldered to the inner jacket of the first tube region ( 31 ). 19. Exhaust gas treatment arrangement according to one of claims 12 to 18, wherein in the front and / or rear end region a as a braid and / or knitted fabric and / or fabric sleeve ( 59 ) made in particular of wire between the catalyst carrier body ( 42 ) and the inner jacket of the first pipe section ( 31 ) is inserted. 20. The exhaust gas treatment arrangement according to claim 19, wherein the catalyst carrier body ( 42 ) is supported at the front end region by the spacer sleeve ( 47 ) and at its rear end region by the wire mesh sleeve ( 59 ) with respect to the first tube region. 21. The exhaust gas treatment arrangement according to claim 19, wherein the wire mesh sleeve ( 59 c) is inserted radially between a region ( 51 c) of the spacer sleeve ( 47 c) which is supported on the first tube region ( 31 c) and the catalyst carrier body ( 42 c).