Exhaust gas treatment assembly

Abstract

An exhaust gas treatment arrangement for an exhaust system of an internal combustion engine comprises a housing (14) elongated in the direction of a housing longitudinal axis (L) and at least one exhaust gas treatment unit (20, 22) arranged in the housing (14) with a jacket (24), wherein at least one bearing / sealing unit (34) with at least two radially successive, nested bearing / sealing rings (42, 44) each interrupted in a circumferential interruption region (46, 48) is arranged in a radial space (36) formed between the jacket (24) and the housing (14), wherein a circumferential interruption region (46) of at least one of the bearing / sealing rings (42, 44) is offset in the circumferential direction with respect to a circumferential interruption region (48) of another of the bearing / sealing rings (42, 44).

Description

[0001] The present invention relates to an exhaust gas treatment arrangement for an exhaust system of an internal combustion engine.

[0002] In exhaust gas treatment systems for internal combustion engine exhaust systems, it is known to install one or more exhaust gas treatment units, such as catalytic converters or particulate filters, as prefabricated assemblies in a housing of such an exhaust gas treatment unit that is elongated in the direction of a housing longitudinal axis, in order to channel essentially the entire exhaust gas flow through them. For defined retention in the housing and to contain leakage flows, at least one bearing / sealing unit, constructed, for example, with wire mesh, is provided in a radial space formed between a casing of such an exhaust gas treatment unit and the housing, surrounding the casing in a ring-like manner.

[0003] An exhaust gas treatment assembly according to the preamble of claim 1 is known from EP 1 342 888 A1. In this known exhaust gas treatment assembly, a bearing / sealing unit comprises several bearing / sealing rings constructed from fiber mats, arranged consecutively in a longitudinal direction of the exhaust gas treatment assembly. In adjacent end regions, directly adjacent bearing / sealing rings overlap one another in the longitudinal direction.

[0004] It is the object of the present invention to provide an exhaust gas treatment arrangement for an exhaust system of an internal combustion engine, in which the formation of leakage flows is avoided by structurally simple measures.

[0005] According to the invention, this object is achieved by an exhaust gas treatment arrangement for an exhaust system of an internal combustion engine according to claim 1. This exhaust gas treatment arrangement comprises a housing which is elongated in the direction of a housing longitudinal axis and at least one exhaust gas treatment unit arranged in the housing and having a casing, wherein in a radial intermediate space formed between the casing and the housing at least one bearing / sealing unit with at least two radially successive, nested bearing / sealing rings, each interrupted in a circumferential interruption region, is arranged, wherein a circumferential interruption region of at least one of the bearing / sealing rings is offset in the circumferential direction with respect to a circumferential interruption region of another of the bearing / sealing rings.

[0006] For a mechanically stable design, even taking into account the thermal load occurring during operation of an exhaust system, at least two bearing / sealing rings, preferably all bearing / sealing rings, of the at least one bearing / sealing unit are designed as metal formed parts, i.e. as so-called metal bead seals.

[0007] By providing several circumferentially interrupted bearing / sealing rings, a very good adaptability of a bearing / sealing unit to the two components that must be supported relative to each other and sealed to prevent leakage is achieved. In particular, unavoidable dimensional tolerances do not impair the support and sealing functions. Since the circumferential interruptions of various bearing / sealing rings of a bearing / sealing unit, which enable adaptability, are offset from each other in the circumferential direction, leakage can essentially not occur in these circumferential areas either.

[0008] In order to achieve an optimal interaction of the bearing / sealing rings of a bearing / sealing unit for a very good sealing effect, we propose that at least two bearing / sealing rings, preferably all bearing / sealing rings, of the at least one bearing / sealing unit are of identical construction to one another.

[0009] A very good sealing effect can be supported by the circumferential interruption areas of at least two bearing / sealing rings of the at least one bearing / sealing unit being offset from one another in the circumferential direction by approximately 180°.

[0010] In order to be able to nest the radially staggered bearing / sealing rings of a bearing / sealing unit well into one another for an efficient sealing effect and to achieve a substantially gas-tight closure in the mutually bridged circumferential interruption regions, it is proposed that the bearing / sealing rings of the at least one bearing / sealing unit have a substantially U-shaped or substantially V-shaped or substantially W-shaped or substantially M-shaped or substantially wave-like cross-sectional profile.

[0011] For an efficient sealing effect, the circumferential interruption area of ​​at least one bearing / sealing ring, preferably each bearing / sealing ring of the at least one bearing / sealing unit, can extend over less than 5%, preferably less than 2%, of the total circumference of the bearing / sealing ring. For example, a design can thus be realized in which such a bearing / sealing ring extends over a circumferential range of 355° to 359°.

[0012] At least one exhaust gas treatment element, preferably a catalyst block and / or a particle filter block, can be arranged in the casing of the at least one exhaust gas treatment unit.

[0013] The invention further relates to an exhaust system for an internal combustion engine, comprising at least one exhaust treatment arrangement constructed according to the invention.

[0014] The present invention is described below with reference to the accompanying figures. Fig. 1 shows a section of an exhaust gas treatment arrangement in an exhaust system for an internal combustion engine with an exhaust gas treatment unit inserted into a housing; Fig. 2 shows detail II of the Fig. 1 enlarged; Fig. 3 shows a schematic representation of an exhaust gas treatment arrangement of the Fig. 1 inserted bearing / sealing unit with two radially consecutive and nested bearing / sealing rings in the direction of view III-III in Fig. 6 ; Fig. 4the two bearing / sealing rings of the sealing unit of the Fig. 3 shown side by side; Fig. 5 the two bearing / sealing rings of the bearing / sealing unit of the Fig. 3 shown side by side; Fig. 6 the two bearing / sealing rings of the Fig. 5 in a nested arrangement when viewed in direction VI in Fig. 3 ; Fig. 7alternative cross-sectional geometries for bearing / sealing rings.

[0015] In Fig. 1 1 shows an exhaust gas treatment arrangement, generally designated 10, of an exhaust system 12 for an internal combustion engine, for example in a vehicle. The exhaust gas treatment arrangement 10 comprises a tubular housing 14, formed, for example, from sheet metal material, which is elongated in the direction of a housing longitudinal axis L and has a largely cylindrical structure. Adjoining the housing 14 at an upstream end region 16 is a deflection housing, generally designated 18. This deflects an exhaust gas flow A flowing through the exhaust system 12 toward the upstream end region 16 of the housing 14.

[0016] In the illustrated embodiment, two exhaust gas treatment units 20, 22 are arranged axially one after the other in the housing 14. Each of these exhaust gas treatment units 20, 22 comprises, as explained in more detail with reference to the exhaust gas treatment unit 22, a substantially tubular casing 24, constructed, for example, from sheet metal, in which two exhaust gas treatment elements 26, 28 are arranged one after the other in the exhaust gas flow direction or the longitudinal axis L of the housing. Catalysts such as oxidation catalysts or SCR catalysts, particulate filters, or the like can be used as such exhaust gas treatment elements 26, 28. It is understood that more than two or even just a single exhaust gas treatment element can be provided inside such a casing 24 and can be held therein, for example, by a surrounding fiber mat or the like.

[0017] During assembly of the exhaust gas treatment arrangement 10, the exhaust gas treatment units 20, 22 to be accommodated in the housing 14 are inserted into the housing from the downstream end of the housing 14 in the direction of the housing's longitudinal axis L. The exhaust gas treatment unit 22 positioned further upstream can be moved until it comes into contact with a radially inwardly bent edge region 30 of the housing 14, thereby predetermining a defined axial positioning.In order to also achieve a defined radial positioning of the exhaust gas treatment units 20, 22, in particular of the exhaust gas treatment unit 22 positioned further upstream, a bearing / sealing unit 32, 34 is provided in at least one axial region, preferably in both axial end regions of the exhaust gas treatment unit 22, which bearing / sealing unit 32, 34 ensures, on the one hand, that the exhaust gas treatment unit 22 is supported in a defined radial direction with respect to the housing 14, and, on the other hand, ensures that the exhaust gas A flowing into the upstream end region 16 of the housing 14 essentially completely enters the interior of the casing 24 and can thus be subjected to a catalytic reaction, for example, in the exhaust gas treatment elements, while essentially no exhaust gas flows through an annular intermediate space 36 formed between the casing 24 and the housing 14.

[0018] An embodiment of such a bearing / sealing unit is described below with reference to the bearing / sealing unit 34 positioned further upstream of the exhaust gas treatment unit 22. Of course, the bearing / sealing unit 32 could also be constructed in the manner described below in the further downstream region of the exhaust gas treatment unit 22. Bearing / sealing units which, if present, are assigned to another exhaust gas treatment unit 20 arranged in the housing 14 can also be constructed in the manner described below.

[0019] The sealing unit 34, which is provided between the two end sections 38, 40 of the housing 14 or the casing 24, which are, for example, slightly deformed radially inward, but are nevertheless essentially cylindrical, and which surrounds the housing longitudinal axis L or the casing 24 essentially in a ring-like manner or over its entire circumference, comprises two bearing / sealing rings 42, 44 arranged radially one after the other with respect to the housing longitudinal axis L and nested within one another. The two bearing / sealing rings 42, 44 are essentially identical to one another and, in the illustrated embodiment, are constructed with an essentially U-shaped cross-sectional geometry. The bearing / sealing rings 42, 44 are formed metal parts made of comparatively thin and therefore flexible sheet material, for example with a thickness of approximately 0.2 mm, and are constructed in the manner of so-called metal bead sealing rings.

[0020] As can be seen from the Fig. 5 and 6As can be seen, the two bearing / sealing rings 42, 44 are not designed as circumferentially closed rings, i.e., rings extending over a circumferential area of ​​360°. Each of the two bearing / sealing rings 42, 44 has a circumferential interruption area 46, 48 in one circumferential area and is therefore designed as an open ring. For example, each of the bearing / sealing rings can extend over a circumferential area in the range of 355° to 359°.

[0021] During assembly of the bearing / sealing unit 34 comprising the two bearing / sealing rings 42, 44, the bearing / sealing rings 42, 44 are positioned or rotated relative to one another such that their circumferential interruption regions 46, 48 are offset from one another in the circumferential direction. Preferably, the arrangement is such that the circumferential interruption region 46 of the bearing / sealing ring 42 positioned further radially inward is offset by approximately 180° relative to the circumferential interruption region 48 of the bearing / sealing ring 44 positioned further radially outward, so that these two circumferential interruption regions 46, 48 are substantially diametrically opposite one another with respect to the housing's longitudinal axis L.

[0022] When assembled, the two bearing / sealing rings 42, 44 are nested in such a way that the two U-shaped legs 50, 52 of the bearing / sealing ring 44 positioned further radially outward generally rest against the outer side of the two U-shaped legs 54, 56 of the bearing / sealing ring 42 positioned further radially inward. The webs 58, 60 of the two bearing / sealing rings 44, 42 connecting the two U-shaped legs 50, 52 and 54, 56, respectively, can generally have a small radial distance from one another prior to assembly of the exhaust gas treatment arrangement 10.

[0023] During assembly and in particular during integration of such a bearing / sealing unit 34 into the exhaust gas treatment arrangement 10, before inserting the exhaust gas treatment unit 22, the bearing / sealing unit 34 comprising the two nested bearing / sealing rings 42, 44 is pushed onto the end section 40 of the casing 24 such that the free ends of the U-shaped legs 54, 56 of the bearing / sealing ring 42 positioned further radially inward rest on the outside of the casing 24. The exhaust gas treatment unit 22 equipped with the bearing / sealing unit 34 is then pushed into the housing 14. At the latest when the bearing / sealing unit 34 reaches the transition to the radially inwardly offset end section 38 of the housing 14, the bearing / sealing ring 44 positioned further radially outward comes into contact with its web 58 on the inner surface of the housing 14 and is pressed radially inward against the bearing / sealing ring 42 positioned further radially inward.Because the bearing / sealing rings 42, 44 are constructed from comparatively thin material and are therefore flexible, they can deform slightly when subjected to such stress, so that on the one hand the two bearing / sealing rings 42, 44 are pressed radially against one another, and on the other hand they are pressed against the housing 14 or the casing 24 and thus essentially over the entire circumference on the one hand provide a defined radial holding effect for the exhaust gas treatment unit 22, and on the other hand also produce an essentially gas-tight closure of the intermediate space 36.

[0024] Due to the fact that the two circumferential interruption regions 46, 48 are offset from one another and thus the bearing / sealing rings 42, 44 bridge one another in these circumferential interruption regions 46, 48, a substantially gas-tight closure of the intermediate space 36 is also ensured in these circumferential interruption regions 46, 48. This is particularly due to the fact that the two bearing / sealing rings 42, 44 are not completely rigid, but can deform due to the radial load exerted by the housing 14 and the casing 24 and thus adapt to their outer circumferential contour and inner circumferential contour, respectively. In particular, this also makes it possible to compensate for shape tolerances or dimensional tolerances of the housing 14 or the exhaust gas treatment unit 22, as well as variations in the radial distance between them generated by thermal expansion of these components.

[0025] The use of such a bearing / sealing unit 34 with two bearing / sealing rings 42, 44 made of comparatively thin-walled and thus easily deformable metal material ensures, on the one hand, that a tight seal that largely excludes leakage flows, particularly in the upstream end region of the housing 14, is realized with comparatively low resistance when the exhaust gas treatment unit 22 is pushed into the housing 14 due to the adaptability of the bearing / sealing unit 34. Since identically constructed bearing / sealing rings 42, 44 can be used for the bearing / sealing unit 34, it can be manufactured with a minimal number of different or differently designed components and is, in particular, dimensionally stable even under the influence of temperature and can adapt to the resulting changes in shape of the components to be sealed against one another when the temperature changes.

[0026] Since the use of such a bearing / sealing unit 34, particularly in the upstream end region of the exhaust gas treatment unit 22 or the housing 14 accommodating it, practically eliminates the occurrence of leakage flows and thus the exhaust gas A to be cleaned of pollutants flows essentially completely through the interior of the casing 24 and therefore the exhaust gas treatment element(s) 26, 28 arranged therein, a different, possibly more cost-effective or easier to implement structure can be selected for the bearing / sealing arrangement 32, which does not necessarily have to ensure the same degree of tightness.If a further exhaust gas treatment unit 20 follows downstream of the exhaust gas treatment unit 22, this could also be supported and sealed with respect to the housing 14, for example at least in its upstream end region, with a bearing / sealing unit which corresponds to the bearing / sealing unit 34 in terms of its structure.

[0027] It should be noted that a wide variety of variations are possible in the design of such a bearing / sealing unit 34. For example, more than two bearing / sealing rings could be arranged nested within one another, which can be particularly advantageous if the radial gap 36 formed between the casing 24 and the housing 14 has a comparatively large radial extent. When using more than two bearing / sealing rings, in order to achieve an efficient sealing effect, it can be provided that the circumferential spacing of the circumferential interruption regions of the bearing / sealing rings corresponds to an angular distance calculated by dividing 360° by the number of bearing / sealing rings used. With three bearing / sealing rings in a bearing / sealing unit, this circumferential spacing of the circumferential interruption regions can therefore be in the range of 120°.With four bearing / sealing rings in a bearing / sealing unit, this circumferential distance of the circumferential interruption areas can be in the range of 90°.

[0028] The bearing / sealing rings of such a bearing / sealing unit can also have different cross-sectional geometries than those in the Fig. 2 bis 4 recognizable U-shaped cross-sectional geometry. Examples of this are in Fig. 7 For example, the bearing / sealing rings used in such a bearing / sealing unit 34 can be designed with a W-shaped cross-sectional geometry, in which the free ends of the two outer W-legs as well as the connecting area between them can be oriented radially outwards, while the two in Fig. 7a ) connecting areas visible below can be oriented radially inwards. As shown in Fig. 7b ), an M-shaped cross-sectional geometry of the bearing / sealing rings is also possible, which essentially reverses the assignment of the support areas to the housing 14 and the shell 24 with regard to the W-shaped configuration. Fig. 7c ) is possible, whereby the two free ends of the V-legs can be oriented either further radially outwards or radially inwards. Finally, the Fig. 7b ) a generally wave-shaped cross-sectional geometry of such a bearing / sealing ring, in which shaft crests follow one another in the axial direction, alternately supported radially outward and radially inward. The number of shaft crests supported radially outward and radially inward can be the same, or, for example, more shaft crests can be supported radially outward than radially inward, or vice versa.

Claims

1. An exhaust gas treatment arrangement for an exhaust gas system of an internal combustion engine, comprising a housing (14) which is elongated in the direction of a housing longitudinal axis (L), and at least one exhaust gas treatment unit (20, 22) which is arranged in the housing (14) and has a shell (24), wherein at least one bearing / sealing unit (34) with at least two bearing / sealing rings (42, 44) which follow one another radially, are nested inside one another and are interrupted in each case in a circumferential interruption region (46, 48) is arranged in a radial intermediate space (36) which is formed between the shell (24) and the housing (14), wherein a circumferential interruption region (46) of at least one of the bearing / sealing rings (42, 44) is offset in the circumferential direction with regard to a circumferential interruption region (48) of another one of the bearing / sealing rings (42, 44), characterized in that at least two bearing / sealing rings (42, 44) of the at least one bearing / sealing unit (34) are configured as metal bead gaskets configured as formed metal parts.

2. The exhaust gas treatment arrangement as claimed in claim 1, characterized in that at least two bearing / sealing rings (42, 44), preferably all the bearing / sealing rings (42, 44), of the at least one bearing / sealing unit (34) are of structurally identical configuration with respect to one another.

3. The exhaust gas treatment arrangement as claimed in claim 1 or 2, characterized in that, in the case of at least two bearing / sealing rings (42, 44) of the at least one bearing / sealing unit (34), the circumferential interruption regions (46, 48) are offset by approximately 180° with respect to one another in the circumferential direction.

4. The exhaust gas treatment arrangement as claimed in one of claims 1 to 3, characterized in that all the bearing / sealing rings (42, 44) of the at least one bearing / sealing unit (34) are configured as formed metal parts.

5. The exhaust gas treatment arrangement as claimed in one of claims 1 to 4, characterized in that the bearing / sealing rings (42, 44) of the at least one bearing / sealing unit have a substantially U-shaped or substantially V-shaped or substantially W-shaped or substantially M-shaped or substantially wave-like cross-sectional profile.

6. The exhaust gas treatment arrangement as claimed in one of claims 1 to 5, characterized in that, in the case of at least one bearing / sealing ring (42, 44), preferably every bearing / sealing ring (42, 44), of the at least one bearing / sealing unit (34), the circumferential interruption region (46, 48) extends over less than 5%, preferably less than 2%, of the overall circumference of the bearing / sealing ring (42, 44).

7. The exhaust gas treatment arrangement as claimed in one of claims 1 to 6, characterized in that at least one exhaust gas treatment element (26, 28), preferably a catalytic converter block and / or particulate filter block, is arranged in the shell (24).

8. An exhaust gas system for an internal combustion engine, comprising at least one exhaust gas treatment arrangement (10) as claimed in one of the preceding claims.

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