EP2000642A2 - Manufacturing method for exhaust gas treatment devices, such as engine exhaust catalysts and particulate filter - Google Patents

Abstract

The present invention relates to a method for producing an exhaust gas treatment device (1) which contains in a tubular housing (4) at least one exhaust gas treatment insert (2), in particular for an exhaust system of an internal combustion engine, in which a circumferential geometry of the at least one insert (2) is measured in at least one axial section of the respective insert (2), in which the at least one insert (2) is inserted axially into the housing (4), - In which the deformation of the housing (4), the measured circumferential geometry of the at least one insert (2) is taken into account.

Description

The present invention relates to a method for producing an exhaust gas treatment device, which contains in a tubular housing at least one exhaust gas treatment insert, in particular for an exhaust system of an internal combustion engine. The invention also relates to an exhaust gas treatment device, in particular for an exhaust system of an internal combustion engine, which contains at least one exhaust gas treatment insert in a tubular housing.

Exhaust gas treatment devices, such as catalysts and particulate filters, have at least one insert which is arranged in a tubular housing. In particular inserts made of ceramic materials are known. Likewise, metallic inserts are known. It is customary to arrange the respective use with the help of a use enveloping the bearing mat in the respective housing. This storage mat has several functions. On the one hand, it dampens lateral accelerations to which the exhaust gas treatment insert may be exposed during operation. On the other hand, the bearing mat can form a thermal insulation to the thermal load of the Reduce housing. Furthermore, a positional fixation of the insert in the housing is regularly achieved with the bearing mat. For this purpose, the bearing mat must be pressed radially between the insert and the housing. For radial compression of the bearing mat, it is known to insert the wrapped with the bearing mat insert into the housing axially, wherein the housing in this state still has an excessive inner cross-section. Subsequently, the housing is compressed, ie radially deformed until the desired compression of the bearing mat is reached.

In ceramic inserts, especially if they are designed as a monolith, the radial compression of the bearing mat is relatively problematic, since it can cause damage to the ceramic inserts when excessive forces occur. Added to this is the fact that the inserts, in particular ceramic monoliths, can have comparatively large dimensional tolerances, as a result of which local stress peaks can occur during the radial deformation of the housing. Furthermore, a gap formed radially between the respective insert and the housing and filled by the bearing mat in the circumferential direction can thus have an uneven, radially measured gap dimension. In the case of unfavorable tolerance chains, the gap dimension can locally become so great that the bearing mat is not sufficiently compressed there, which during operation can lead to the bearing mat being detached at this inadequately compressed point, as a result of which a bypass that forms the insert is formed in the housing.

From the US 6,954,988 B2 For example, a method for producing catalysts is known in which a breaking characteristic of the ceramic monolith is first determined, which depends on the particular combination of ceramic material and bearing mat material. This breakage characteristic includes in particular the dependence of the forces occurring during pressing of the bearing mat on the speed with which the pressing is carried out. In the known method, the pressing of the bearing mat is now carried out so that damage to the monolith is avoided.

The present invention is concerned with the problem of providing an improved embodiment for a manufacturing method of the type mentioned at the outset or for an exhaust gas treatment insert of the type mentioned above, which is characterized in particular by reducing the risk of damage to the insert during manufacture and / or that a comparatively uniform gap progression in the circumferential direction is achieved.

This problem is solved by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of measuring the circumferential geometry at least in an axial section during the respective use prior to introduction into the housing and to take into account the measured circumferential geometry during the subsequent deformation of the housing. This can take into account the deformation of the housing in particular tolerance-related form deviations of the respective use. As a result, on the one hand voltage peaks can be avoided. On the other hand, the radial compression of the bearing mat can be realized more uniformly.

In particular, the method can be carried out such that, at least in an axial section of the housing assigned to the respective axial section of the at least one insert, a circumferential geometry of the housing is deformed in dependence on the measured circumferential geometry of the at least one insert such that a radially between the housing and the housing at least one insert trained gap sets a predetermined gap profile in the circumferential direction. In particular, the predetermined gap progression can take into account optimum compression of the bearing mat. Likewise, the predetermined gap profile can take into account anisotropic load limits of the respective insert. Since the achievable gap size correlates with the radial compression of the bearing mat and thus with the forces occurring during pressing, the load of the respective insert during deformation of the housing can be determined by specifying the gap dimension.

According to an advantageous embodiment, the respectively measured circumferential geometry of the respective insert can be assigned to predetermined circumferential segments of the insert, in which case, in addition, for the respective circumferential segment, an averaged peripheral geometry from those in the respective circumferential segment measured circumferential geometry values is determined. The deformation of the housing is then also in circumferential segments which are assigned to the circumferential segments of the respective insert, wherein the deformation of the housing in the housing-side circumferential segments takes into account the averaged circumferential geometries. This procedure takes into account in particular deformation tools distributed in the circumferential direction, arranged segmented moldings.

The detection and consideration of the circumferential geometry of the respective insert takes place at least in an axial section of the insert. It is clear that in other embodiments, several axial sections can be measured with respect to their circumferential geometry. Accordingly, a corresponding number of axial sections of the housing can then also be deformed during the deformation of the housing as a function of the respectively measured peripheral geometries. In principle, any resolution in the longitudinal direction is conceivable. For example, the complete outer contour of the respective insert may be e.g. be detected by so-called 3-D scanning. Thus, in addition, a longitudinal geometry of the respective insert during deformation of the housing can be taken into account.

An exhaust gas treatment device which is produced by the method according to the invention can be characterized, for example, by the fact that the housing has a cross-section adapted to the cross-section of the insert, even if the respective insert has an asymmetrical cross-section with respect to rotations about its longitudinal central axis. The cross-section of the housing then shapes the respective asymmetry of the insert more or less exactly.

Ceramic monoliths, the cell matrix of which has a lattice of mutually perpendicular webs, have a pressure load capacity that varies from the rotational position. Parallel to webs of the respective monolith is higher loadable than in the diagonal direction of the cells. The dependence of the compressive strength of the respective use of its rotational position can be taken into account when deforming the housing. Thus, an exhaust gas treatment device, which has been produced by the process according to the invention, in particular also characterized in that the housing is formed in an axial portion associated with the respective application so that adjusts a course in the circumferential direction for the radial gap geometry, one of the radial, with the rotational position varying pressure load capacity of the respective use dependent course taken in the circumferential direction of the radial compression of the bearing mat.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained not only in the combination given, but also in others Combinations or alone, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Fig. 1

einen stark vereinfachten, prinzipiellen Verlauf eines Herstellungsverfahrens,

Fig. 2 und 3

jeweils einen stark vereinfacht dargestellten, prinzipiellen Querschnitt eines Abgasbehandlungseinsatzes, bei verschiedenen Ausführungsformen,

Fig. 4

einen Längsschnitt entsprechend der Position V in Fig. 1 durch eine Abgasbehandlungseinrichtung beim Verformen ihres Gehäuses entsprechend Schnittlinien IV in Fig. 5,

Fig. 5

einen Querschnitt durch die Abgasbehandlungseinrichtung aus Fig. 4 entsprechend Schnittlinien V in Fig. 4,

Fig. 6

einen Längsschnitt wie in Fig. 4, jedoch bei einer anderen Ausführungsform entsprechend Schnittlinien VI in Fig. 7,

Fig. 7

einen Querschnitt wie in Fig. 5, jedoch bei der Ausführungsform aus Fig. 6 entsprechend Schnittlinien VII in Fig. 6.

Show, in each case schematically,

Fig. 1

a greatly simplified, fundamental course of a manufacturing process,

FIGS. 2 and 3

in each case a basic cross-section of an exhaust gas treatment insert shown in greatly simplified form, in various embodiments,

Fig. 4

a longitudinal section corresponding to the position V in Fig. 1 by an exhaust gas treatment device when deforming its housing according to section lines IV in Fig. 5 .

Fig. 5

a cross section through the exhaust treatment device Fig. 4 according to section lines V in Fig. 4 .

Fig. 6

a longitudinal section as in Fig. 4 but in another embodiment according to section lines VI in FIG Fig. 7 .

Fig. 7

a cross section as in Fig. 5 , but in the embodiment of Fig. 6 according to section lines VII in Fig. 6 ,

Corresponding Fig. 1 are used to produce an exhaust gas treatment device 1, which in Fig. 1 is shown only in an unfinished state, at least one exhaust treatment insert 2, at least one bearing mat 3 and a tubular housing 4 is required. The exhaust gas treatment device 1 may be, for example, a particle filter or a catalyst. The exhaust gas treatment device 1 preferably serves for use in an exhaust system of an internal combustion engine, which can be arranged in particular in a motor vehicle. The exhaust gas treatment insert 2, which is also referred to below as the insert 2 in the following, can thus be preferably a particle filter insert or a catalyst insert. The insert 2 can basically consist of a metallic material. However, the insert 2 preferably consists of a ceramic material. In particular, the insert 2 is formed by at least one ceramic monolith. The insert 2 may consist of a single monolith; Similarly, the insert 2 can be assembled from several monoliths.

The bearing mat 3 may be a wire mesh made of stainless steel or a fiber mat made of a non-combustible material. The bearing mat 3 is compressible, but it develops a certain spring elasticity, which can be used in the mounted exhaust gas treatment device 1 for fixing the position of the insert 2 in the housing 4.

Corresponding Fig. 1 At I at least in an axial section of the insert 2, a peripheral geometry of the insert 2 is measured. A corresponding measuring device is denoted by 5 here. To detect the circumferential geometry, a rotation 6 between the insert 2 and the measuring device 5 may be required. The circumferential geometry can be measured in a single axial section. It is assumed that the insert 2, which is produced in particular by the extrusion process, has a circumferential geometry that is constant in the axial direction. Preferably, however, the insert 2 is measured in several axial sections. It is also possible to continuously measure the insert 2 in the axial direction, ie, the axial geometry of the insert 2 is also measured. For this purpose, an axial adjustment 7 between the insert 2 and the measuring device 5 take place.

The measurement of the insert 2 is preferably carried out with respect to a mark 8, which is symbolized here by a cross. This marking 8 can be present anyway on the respective insert 2, for example in the form of a longitudinal groove formed on the insert 2 during production. Likewise, the mark 8 can be attached to the insert 2 in a targeted manner become. For example, a line can be attached to the insert 2 with paint or the like.

In II, the insert 2 is provided with the bearing mat 3. The wrapped with the bearing mat 3 insert 2 is shown at III. The wrapped with the bearing mat 3 insert 2 is now inserted in the axial direction in the housing 4, which is shown at IV. For axial insertion, in particular, an insertion funnel can be used. In any case, the housing 4 has an excess, whereby the axial insertion of the provided with the still unpressed bearing mat 3 insert 2 is facilitated.

At V, the deformation of the housing 4 is now carried out. Corresponding molding tools are designated by 9 in this case. The radial deformation of the housing 4 is required to achieve a desired radial compression of the bearing mat 3. Only through this radial compression can the bearing mat 3 fulfill its fixing effect or fixation function. Among other things, the compressed bearing mat 3 is used to fix the insert 2 relative to the housing 4. When the housing 4 is deformed, the circumferential geometry previously measured at I and, if appropriate, the measured axial geometry are taken into account.

In particular, a corresponding, not shown here control of the forming tool 9, the measured circumferential geometry or axial geometry such that for a gap 10, the radially between the housing 4 and the Insert 2 forms and in which the bearing mat 3 is arranged, sets a predetermined gap profile in the circumferential direction.

Depending on the design of the forming tool 9, it may be expedient to assign the measured circumferential geometry to predetermined circumferential segments of the insert 2 and to determine an average circumferential geometry for the circumferential segments, which can be calculated from the circumferential geometry measured within the respective circumferential segment. For example, the forming tool 9 in the circumferential direction six forming bodies, with which the housing 4 can be radially deformed. Accordingly, the insert 2 is subdivided into six peripheral segments, to each of which an average circumferential geometry is assigned from the peripheral data measured within the respective circumferential segment. When forming the housing 4, the circumferential geometry of the housing 4 can then also be deformed in circumferential segments which are assigned to the peripheral segments of the respective insert 2 as a function of the averaged circumferential geometries. In the example, the six forming bodies are then driven individually according to the averaged circumferential geometries of the insert 2, whereby the housing 6 is also individually deformed along its circumference in six circumferential segments.

Depending on the configuration of the available forming tool, the circumferential geometry of the insert 2 on the housing 4 in a single axial section or in several Axial sections or quasi to be implemented continuously in the axial direction. Accordingly, the axial course of the peripheral geometry of the housing 4 can be deformed as a function of the axial course of the circumferential geometry measured in the insert 2 such that a predetermined gap progression can also be established in the axial direction. Depending on the forming tool 9, it may also be expedient here to assign the axially measurable axial course of the circumferential geometry of the insert 2 to predetermined axial sections of the insert 2 and to determine an average circumferential geometry for the respective axial section from the measured values. The housing 4 can then also be deformed in axial sections, which are assigned to the predetermined axial sections of the insert 2, as a function of the averaged circumferential geometries.

For the forming process of the housing 4, it may be appropriate to consider the mark 8. For example, the forming tool 9 can automatically detect the respective marking 8. Likewise, it may be necessary to insert the respective insert 2 with respect to its mark 8 with a predetermined rotational position and / or axial position in the housing 4. The deformation of the housing 4 then takes place with respect to the mark 8.

After deformation of the housing 4, the bearing mat 3 is radially compressed, which can be seen in VI. For quality assurance can be provided at VI, the formed by the deformation of the housing 4 actual geometry of the housing 4 or to measure the actual geometry of the gap 10. Corresponding measuring devices are denoted by 11 here. Depending on the geometry measured on the insert 2 at I, a desired geometry for the housing 4 or for the gap 10 can be determined, which can then be compared with the actual geometry measured at VI. By a feedback 12, the forming tool 9 or a forming device equipped therewith can be automatically adapted in dependence of this target-actual comparison.

As explained above, it is possible by means of the procedure according to the invention for the respective exhaust-gas treatment device 1 to set a predetermined course of the gap in the circumferential direction and / or in the axial direction more or less accurately. This gap profile may in particular be selected such that a substantially constant gap dimension is established in the circumferential direction or in the axial direction. For example, shows Fig. 2 an embodiment in which the exhaust gas treatment device 1 between the insert 2 and the housing 4 has a gap 10 in which the bearing mat 3 is arranged. The gap profile in the circumferential direction is characterized here in that the gap 10 has a substantially constant gap dimension in the circumferential direction. The gap dimension here is the gap width 13 or gap width measured in the radial direction. Fig. 2 shows in an exaggerated view of an insert 2, which has an asymmetrical with respect to rotations about its longitudinal central axis 14 cross-section. It is characteristic of this embodiment of the exhaust gas treatment device 1 that its housing 4 at least in the axial portion assigned to the insert 2 has a cross section which is adapted to the asymmetrical cross section of the insert 2. The housing 4 follows the irregularities of the outer contour of the insert. 2

Fig. 3 also shows in exaggerated view a particular embodiment in which the insert 2 is formed from at least one ceramic monolith 15. The monolith 15 has a cell matrix 16 which has a grid of webs 17 extending perpendicular to one another. Such a monolith 15 has anisotropic load capacity for radial pressure loads. For compressive loads that run parallel to webs 17, the compressive strength of the monolith 15 is greater than under compressive loads, which are inclined relative to the webs 17. In particular, the compressive strength is smallest in the direction of diagonals 18 of the grid.

The predetermined in the circumferential direction or in the axial direction gap profile can now be selected specifically for the deformation of the housing 4 so that the occurring during deformation of the housing 4 radial compressive load of the insert 2 in response to varying with the rotational position or axial position compressive strength of the insert 2 takes place. This means that in particular the anisotropic compressive strength of the insert 2 during pressing of the bearing mat 3 is taken into account. This can be done in areas that have a higher Have compressibility, a stronger compression of the bearing mat 3 can be achieved.

Corresponding Fig. 3 is in an exhaust gas treatment device 1, which has been prepared under this condition, the housing 4 is formed at least in one of the respective insert 2 associated axial portion that sets in the circumferential direction for the radial gap geometry a course, one of the radial, with the Rotational position varying compressive strength of the insert 2 dependent course of the radial compression of the bearing mat 3 in the circumferential direction taken into account. In the specific example shown, the radial compression of the bearing mat 3 in circumferential segments 19, in which the webs 17 are oriented perpendicular to the housing 4 at least in a central region of the respective segment 19, greater than in other circumferential segments 20, in which the webs 17 at least in a central region of the respective peripheral segment 20 are inclined by about 45 ° relative to the housing 4. In these other circumferential segments 20, in particular, the diagonals 18 are oriented at least in a central region of the respective segment 20 substantially perpendicular to the housing 4.

The Fig. 4 to 7 show purely by way of example and without limiting the generality of two different embodiments of forming tools 9, with the aid of the housing 4 in the circumferential direction and / or longitudinally segmentally different deformed to the desired cross-sectional shape or gap profile in the circumferential direction or in To achieve longitudinal direction. For example, the forming tool 9 in the in Fig. 4 to 7 shown examples equipped with a plurality of tool segments 21 which are arranged distributed in the circumferential direction and each associated with a circumferential segment of the housing 4. For the forming process, the tool segments 21 are loaded in the radial direction according to arrows. The individual tool segments 21 can be driven individually with this radial contact pressure. The individual tool segments 21 are preferably each controlled away. In this way, each individual tool segment 21 can be assigned an averaged peripheral geometry, which is then realized on the housing 4 in the region of the respective circumferential segment.

In the Fig. 4 and 6 the bearing mat 3, the housing 4 and the gap 10 are marked in the undeformed state with a, while their deformed state is marked with b. The tool segments 21 can be shorter in the axial direction than the housing 4. In this way, different axial sections of the housing 4 can be individually shaped, that is, with different average cross-sectional geometries in the region of the respective tool segments 21.

While in the embodiment of the 4 and 5 the tool segments 21 are configured as forming jaws, show the 6 and 7 an embodiment in which the tool segments 21 are designed as forming rollers, which are also referred to in the following as 21. The forming rollers 21 are in terms of their geometry to the outer contour of the housing 4 adapted what is in Fig. 7 is clearly visible. When forming an axial relative movement between the housing 4 and the forming rollers 21 can be performed. For example, the housing 4 can be pressed or pulled axially through the stationarily arranged forming rollers 21. This results in the desired deformation of the housing 4 in the radial direction, namely segmentally corresponding to the circumferentially distributed and each associated with a peripheral segment forming rollers 21. The forming rollers 21 are applied for the deformation of the housing 4 in the radial direction with a corresponding contact force, the in Fig. 7 represented by arrows. Again, the forming rollers 21 are preferably path-controlled. In this embodiment, it is basically possible, when pulling or pushing through the housing 4 centrally through the forming rollers 21 to set them differently for different axial sections of the housing 4, specifically individually. This can theoretically be done continuously. However, an embodiment is preferred in which the respective setting of the forming rollers 21 is constant for a plurality of axially successive axial sections, whereby the advancement of the housing 4 for adjusting the forming rollers is interrupted by specifying new values for the cross-sectional geometry.

Claims (12)

Method for producing an exhaust gas treatment device (1) which contains in a tubular housing (4) at least one exhaust gas treatment insert (2), in particular for an exhaust system of an internal combustion engine, in which a circumferential geometry of the at least one insert (2) is measured in at least one axial section of the respective insert (2), in which the at least one insert (2) is inserted axially into the housing (4), - In which the deformation of the housing (4), the measured circumferential geometry of the at least one insert (2) is taken into account. Method according to claim 1,
characterized,
in that a peripheral geometry of the housing (4) is deformed at least in an axial section of the housing (4) assigned to the respective axial section of the at least one insert (2) as a function of the measured circumferential geometry of the at least one insert (2), such that a radial between the housing (4) and the at least one insert (2) formed gap (10) adjusts a predetermined gap profile in the circumferential direction. Method according to claim 1 or 2,
characterized, that the measured circumferential geometry of the respective insert (2) is assigned to predetermined circumferential segments and an average circumferential geometry is determined for the respective circumferential segment, - That the peripheral geometry of the housing (4) in the peripheral segments of the respective insert (2) associated circumferential segments is deformed in dependence of the averaged circumferential geometries. Method according to one of claims 1 to 3,
characterized, in addition that the axial course of the circumferential geometry of the respective insert (2) is measured, - That the axial course of the peripheral geometry of the housing (4) is deformed in dependence on the measured profile of the respective insert so that adjusts a predetermined gap profile in the axial direction. Method according to claim 4,
characterized, that the measured axial course of the circumferential geometry of the respective insert (2) is assigned to predetermined axial sections and an average circumferential geometry is determined for the respective axial section, - That the axial course of the housing (4) in the axial sections of the respective insert (2) associated axial sections is deformed depending on the averaged circumferential geometries. Method according to one of claims 1 to 5,
characterized, - that the measurement of the insert (2) with respect to a respective insert (2) existing or mounted mark (8) is performed, - That the respective insert (2) with respect to its mark (8) with a predetermined relative position in the housing (4) is inserted, so that the deformation of the housing (4) with respect to the marking (8) of the respective insert (2). Method according to one of claims 1 to 6,
characterized,
that the predetermined in the circumferential direction and / or in the axial direction gap profile is selected so that in the circumferential direction and / or in the axial direction sets a substantially constant gap (13). Method according to one of claims 1 to 7,
characterized,
that the predetermined in the circumferential direction and / or in the axial direction gap profile is selected so that the deformation of the housing (4) occurring radial compressive load of the at least one insert (2) in response to varying with the rotational position and / or axial pressure load capacity of the at least one insert (2) takes place. Method according to one of claims 1 to 8,
characterized, - that by the deformation of the housing (4) formed actual geometry of the housing (4) and / or of the gap (10) is compared with measured a determined function of the measured geometry of the at least one insert (2) target geometry . - That a deforming the housing (4) performing forming device is automatically adapted depending on the target-actual comparison. Exhaust gas treatment device, in particular for an exhaust system of an internal combustion engine, with a tubular housing (4) into which at least one exhaust gas treatment insert (2) is inserted,
characterized, - that the respective insert (2) has an asymmetrical cross-section with respect to rotations about its longitudinal central axis (14), - That the housing (4) in one of the respective insert (2) associated with the axial section of the asymmetrical cross-section of the respective insert (2) adapted cross-section. Exhaust gas treatment device, in particular for an exhaust system of an internal combustion engine, with a tubular housing (4), in which at least one exhaust gas treatment insert (2) is inserted, wherein radially between the housing (4) and the respective insert (2) a gap (10) containing a bearing mat (3) is formed whose radial gap geometry (13) determines a radial compression of the bearing mat (3),
characterized,
in that the housing (4) is shaped in an axial section assigned to the respective insert (2) so that a course for the radial gap geometry is established in the circumferential direction, which course of the radial movement depends on the radial compressibility of the respective insert which varies with the rotational position Compression of the bearing mat (3) taken into account in the circumferential direction. Exhaust treatment device according to claim 11,
characterized, in that the at least one insert (2) has at least one ceramic monolith (15) whose cell matrix (16) has a grid of mutually perpendicular webs (17), - That the radial compression of the bearing mat (3) in a circumferential segment (19), in the middle of the webs (17) are oriented perpendicular to the housing (4) is greater than in another circumferential segment (20), in the middle of the webs (17) are inclined by about 45 ° relative to the housing (4).

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