DE102004004002B4 - particulate Filter - Google Patents

Abstract

Particulate filter (1) for an internal combustion engine, in particular in a motor vehicle, comprising at least one filter body (2) and a jacket tube (3) surrounding the filter body (2),
- wherein the jacket tube (3) opens upstream in an input channel (4) and downstream in an output channel (5),
- wherein the jacket tube (3) at least to the output channel (5) towards a funnel (6), in particular concentrically, tapers,
- wherein the filter body (2) is supported axially on the jacket tube (3) and / or on the funnel (6) and / or on the outlet channel (5),
characterized,
in that the axial support of the filter body (2) on its output side (7) is spaced from its outer peripheral edge (8).

Description

The The present invention relates to a particulate filter for an internal combustion engine, in particular in a motor vehicle, having the features of the preamble of claim 1.

Such a particle filter is for example from EP 1 348 839 A2 known, which has a jacket tube, which opens on the inflow side via an inlet funnel into an inlet channel and the downstream side via an outlet funnel into an outlet channel. In the jacket tube, a filter body is arranged, which is enveloped radially inwardly by an inner retaining cylinder and radially outwardly by an outer retaining cylinder. The retaining cylinders are permeable to gas and thus allow a radial flow through the filter body. The retaining cylinders are attached at their axial ends on the jacket tube. Between the outer retaining cylinder and the jacket tube, an annular space is formed, which leads to the exit funnel. In the known particle filter, the filter body is axially supported on the downstream side of the jacket tube along its axial end face.

From the DE 198 21 872 A1 a catalyst is known which comprises a carrier in a housing between an inlet and an outlet, which is provided with a catalytically active coating and can be flowed through by exhaust gas. In this case, the carrier consists of a filling made of crystalline alumina in fibrous form.

exhaust of internal combustion engines, both of diesel engines as well of gasoline engines, contain easily respirable particles, in particular Soot particles. To remove these particles from the exhaust gases, it is known in an exhaust line of the internal combustion engine, a particulate filter, in particular a soot filter, to arrange one for the Permeable exhaust gases filter body contains but for the excreted particles is impermeable. As filter body comes for example, a monolithic or one composed of filter segments Filter in question, on or in which the filtered-out particles while deposit the filter operation. By the increasing deposit sets the filter body gradually too, so that the flow resistance of the particulate filter increases with increasing load. To the filter effect of It is necessary to obtain the particulate filter in the long term To regenerate particulate filters from time to time. The regeneration the particulate filter is made by burning the stored therein Particle.

Especially just before the regeneration of the particulate filter is a pressure load in the filter body due the deposited, but not yet burnt-off particles particularly high, causing the filter body high axial forces can act. In aged particulate filters with filter segments composed of especially glued together, filter bodies, can be too high axial force to shearing off individual filter segments at common segment boundaries to lead and thereby reduce the efficiency of the particulate filter. In order to record the described high axial forces and at the same time a shearing off of the individual filter segments at their Can prevent segment boundaries conventional Particle filter, z. B. with a friction-generating circumferential bracing be provided with ceramic fiber bearing mats, which, however, often unable to keep the filter body safe in all conditions to keep.

Furthermore can the axial forces in principle also through the additional Installation of an axial cushion made of pressed wire mesh with stop ring be taken at an edge region of the filter, however very high pressure at the outer edges the filter body that can easily cause damage (Edge chipping) to lead can. Furthermore results in a poor pressure distribution on the cushion pad as a result of misalignment between a filter body support surface and a ring layer.

Of the on the circumference of the filter body arranged stop ring increases especially in these areas a flow resistance of the filter body, what to a different temperature distribution between well-flown and flowed through less well Areas and thus can lead to critical thermal voltages. A consequence of such critical thermal stresses within the filter body can for example, so-called ring-off cracks.

Here implements the invention. The present invention is concerned with the problem, for a particulate filter of the type mentioned an advantageous embodiment indicate, in particular, an improved support of the filter body in Particle filter allows and more even Loading and regenerating the filter body guaranteed.

This Problem is inventively the subject of the independent Claim solved. Advantageous embodiments are the subject of the dependent Claims.

The invention is based on the general idea, in a particulate filter for an internal combustion engine, in particular in a motor vehicle, which comprises at least one filter body and a jacket tube surrounding the filter body, the filter body spaced on its output side axially supported by its outer peripheral edge. In this case, the jacket tube opens into an inlet channel on the inflow side and into an outlet channel downstream, with the jacket tube tapering at least in the direction of the outlet channel with a funnel, which is in particular concentric. The inventive axial support of the filter body on its output side can be done on the jacket tube and / or on the funnel and / or on the output channel.

The inventive solution offers the advantage that the filter body in comparison to a merely marginal circumferential clamping even or stored in the area of greater axial load and supported is. Furthermore can thereby a loading of the filter body and a regeneration the same more uniform. Furthermore, guaranteed spaced from the outer peripheral edge support, that the flow in the Edge area is not obstructed and thus an insulating effect of not flowed through outer channels to a Core of the filter body be avoided in conjunction with critical thermoelectric voltages. The Avoidance of critical temperature stresses between a core and an edge region of the filter body reduced in addition the risk of a so-called ring-off crack.

Furthermore prevents the more uniform axial according to the invention support of the filter body high local pressures on the circumference of the filter body, thereby damaging Edge breakouts and accompanied by a deterioration in the efficiency of the Particulate filter can be avoided. A hitherto occurring change a size of the bearing surface and so that a local Pressing by a not exactly concentric position of the filter body and casing or casing pipe and tolerances of the filter body cross-section can also avoided by the support according to the invention be like a bad pressure distribution on the cushion pad as a result of misalignment between filter body support surface (angularity on the filter body) and ring location.

According to one advantageous development is or are at one of several Filter segments formed filter body at least one Drahtgestrickkissen and / or a holding frame designed and arranged such that the at least one wire mesh pillow almost all filter segments individually supports and / or that the at least one wire mesh cushion at least two filter segments supported in the region of a common filter segment boundary. hereby can be achieved in a particularly simple and efficient way, that even on aged filter bodies, for example, with partial loose bonding between individual Filter segments, the slipping out of individual segments avoided becomes. additionally is by the support in the area of the filter segment boundaries a smaller hindrance of a Filter flow achieved, since there is no flow in this area anyway. This has the consequence that a flow cross-section of the filter body in essential is not reduced and thereby a back pressure at loaded filter not additional through the filter body cross-section restrictive Wire knitted cushion increased becomes.

According to one preferred development is the wire mesh pillow of a Holding frame supported, which is supported on the output channel and arranged at a free end of the extended to the filter body output channel is. As a result, in a particularly simple manner, the support of the Holding frame and thus the support of the wire knit cushion or the filter body at the inwardly extended Output channel causes. Especially with regard to production this can be support make it particularly easy by making the output channel not flush with the funnel, but axially overlapping by a defined distance is arranged with the same. An additional support, for example via additional segments This is not required, so that the material costs and reduce the manufacturing costs.

Corresponding A preferred embodiment of the invention is the output channel at the extended Section radially permeable to exhaust gas, especially perforated or perforated. This ensures that that the exhaust gas from the outer annulus outside of the wire knit cushion can flow freely and thereby uniform flow through the Particulate filter and an associated uniform loading the same with soot particles guaranteed can be.

According to a vorberzugzugten embodiment of the invention, the extended portion of the outlet channel flow baffles, in particular dents and / or indentations, such that a flow resistance within the extended portion is about as large as outside. This has the effect that an outflow resistance in the center of the filter body, that is to say in a region within an outlet channel cross section, is similar to that in the region outside the cross section of the outlet channel and thus an uneven flow through the filter over the cross section and an associated uneven soot loading can be avoided , Since a regeneration capability of the particulate filter is closely tied to a uniform loading of the filter body with soot particles, the uniform loading of the particulate filter or by the uniform flow through the same ge efficiency of the particulate filter at a high level to hold.

Further important features and advantages of the invention will become apparent from the Dependent claims, from the drawings and from the associated description of the figures the drawings.

It it is understood that the above and the following yet to be explained features not only in the specified combination, but also in other combinations or alone, without to leave the scope of the present invention.

One preferred embodiment The invention is illustrated in the drawings and is in the following description explains the same reference numerals to the same or functionally identical or similar Refer to components.

It show, in each case schematically,

1a a particle filter according to the invention with a support of a filter body on an extended outlet channel,

1b a representation like in 1a but with a support on a funnel,

1c a representation like in 1a , but with a support on a jacket tube,

2a to 2f in each case a cross section through the particulate filter and the filter body with different imple mentation of axial brackets.

3 an output side of the particulate filter with a wire knit cushion and a holding frame in detail.

Corresponding 1 has a particle filter according to the invention 1 a housing 18 in which a filter body 2 is arranged. The housing 18 is adapted for installation of an exhaust line, not shown, of an internal combustion engine, also not shown, in particular a diesel engine. During operation of the internal combustion engine, which may preferably be arranged in a motor vehicle, then results in a flow through the particulate filter 1 or of the filter body 2 , in the 1 through arrows 19 is symbolized. Depending on the direction of flow 19 thus results for the particulate filter 1 an inflow side with an input channel 4 and a downstream side with an output channel 5 , According to 1 is the filter body 2 from a jacket pipe 3 surrounded, which is at least the output channel 5 , here also to the entrance channel 4 out, with a funnel 6 , in particular concentric, rejuvenated.

When operating the particulate filter 1 Particles, in particular soot particles, enter the filter body 2 and get stored there. Over time, this deposition of the particles leads to a decrease in the flow cross-section of the filter body 2 , which must then be regenerated from time to time by burning the soot particles. In particular, just before an upcoming regeneration process, that is, with a filter body heavily loaded with particles 2 , Due to the constricted flow cross-section, an increased back pressure, which makes it necessary that the filter body 2 against the flow direction 19 is supported. According to the invention, the filter body 2 to it at its output side 7 spaced from its outer peripheral edge 8th axially on the output channel 5 (see 1a ) and / or at the funnel 6 (see 1b ) and / or on the jacket tube 3 (see 1c ) supported.

According to the 1a to 1c contains the filter body 2 several parallel durchströmmare, preferably monolithic filter segments 9 which have, for example, a rectangular or hexagonal cross-section. The filter body 2 is for example made of a ceramic, in particular silicon carbide or cordierite. Usually, the filter body 2 either produced monolithically as a whole or, as described above, from individual monolithic filter segments 9 which, for example, at common filter segment boundaries 12 glued together, assembled.

Neighboring filter segments 9 and 9 ' thus have a common filter segment boundary 12 , this at the same time an unspecified wall between the two filter segments 9 . 9 ' forms, which is permeable to exhaust gases and which is impermeable to the particles to be filtered out of the exhaust gases out. This is achieved, for example, by an appropriate selection of the material for the filter body 2 so that it is correspondingly porous, for example. When flowing through, the particles entrained in the exhaust gas flow settle in the area of the walls of the individual filter segments 9 from.

The settling of the filtered-out particles leads to an increase in the back pressure within the particle filter with increasing time 1 and thus to an axial load of the filter body 2 in the flow direction 19 , To the filter body within the jacket tube 3 To fix, in principle, a friction-generating circumferential bracing can be realized with ceramic fiber bearing mats. However, this is regularly not able to filter body 2 safe to keep under all operating conditions. Likewise, axial cushions made of pressed wire mesh with a stop ring at the peripheral edge 8th of the filter body 2 are not sure that the filter body 2 safe in the jacket pipe under all operating conditions 3 remains fixed.

Therefore, the solution according to the invention, as mentioned above, proposes an axial support of the filter body 2 at its exit side 7 with wire mesh pillow 10 before, with the support spaced from the outer peripheral edge 8th of the filter body 2 axially on the casing pipe 3 and / or at the funnel 6 and / or on the output channel 5 he follows. Such an axial support, spaced from the peripheral edge 8th Prevents previously occurring high pressures in the region of the peripheral edge 8th and thereby helps to reduce damage, especially edge breakouts. Furthermore, the invention offers the advantage that a non-concentric position of the filter body 2 in the case 18 as well as the tolerances of the filter body cross-section a size of the bearing surface and a local pressure compared to a support with a peripheral edge 8th arranged stop ring is not or not significantly changed. This makes it easier to apply high axial pressures without major variations in local pressure. In addition, a poor pressure distribution on a cushion pad as a result of a misalignment between the filter body support surface and the position of the previously used stop ring can be avoided.

According to the 1a to 1c as well as the 2a to 2f the axial support of the filter body takes place 2 with the help of at least one wire knit cushion 10 at the exit side 7 of the filter body 2 is applied. Preferably, the wire mesh pillow is 10 while essentially centered on the filter body 2 arranged.

It is also conceivable that the wire mesh pillow 10 from a support frame 11 is held on the casing pipe 3 and / or at the funnel 6 and / or on the output channel 5 supported.

At out of filter segments 9 composite particulate filters 1 are the wire mesh pillows 10 at the exit side 7 of the filter body 2 expediently arranged so that they all possible filter segments 9 . 9 ' etc. individually support. This is due to aged filter bodies 2 with partially loose connection or bonding between the individual filter segments 9 . 9 ' etc., slipping out of individual filter segments 9 avoided. Generally, the wire mesh pillow 10 as well as the support frame 11 gas-permeable to obstructing the filter flow through the wire knit cushions 10 or through the support frame 11 to avoid. For example, the holding frame 11 made of perforated metal.

Another criterion for the arrangement of the wire knitted cushions 10 is the least possible obstruction of the filter flow. Preference is given to the wire knit cushions 10 therefore in the range of a common filter segment boundary 12 two filter segments 9 and 9 ' arranged, since there is no flow anyway.

For very large particle filters 1 , z. B. in commercial vehicles, you will get the wire mesh pillow 10 preferably in the aforementioned holding frame 11 holders, which either on the jacket tube 3 or at the funnel 6 are supported.

Especially with smaller particle filters 1 with, for example, concentric funnels 6 It makes sense, the wire knitted cushions 10 or the holding frame 11 at the free end 15 to the filter body 2 extended output channel 5 to arrange (cf. 1a ). During assembly, the wire mesh cushions are used 10 against the filter body 2 pressed. To ensure that the cleaned exhaust gas is unhindered by the outer annulus 20 in the output channel 5 can flow out, is the output channel 5 at its extended section 16 radially permeable to gas, in particular perforated or perforated, formed. Possibly. has the extended section 16 to reduce a flow velocity flow baffles 17 , in particular dents and / or indentations (cf. 2f ), causing a flow resistance within the extended section 16 and thus the flow velocity is about as great as in the outer annulus 20 , This can cause an uneven flow through the particle filter 1 over the cross section of the filter body 2 and thus an uneven soot loading and thus a deterioration of the efficiency of the particulate filter 1 be avoided.

According to the 2a to 2f are different embodiments for the axial support of the filter body 2 on the output side 7 shown. This can be at least one wire mesh pillow 10 and / or the support frame 11 be designed so that on the output side 7 an annular (cf. 2f ) or rectangular (compare 2a , c and e) support zone 13 formed. In general, it is also conceivable that the holding frame 11 several separate support segments 14 has, on the jacket tube 3 and / or at the funnel 6 and / or on the output channel 5 are supported.

Corresponding 2 B can the support segments 14 have a scoop-shaped cross section, so that in the flow through the particulate filter 1 a defined exhaust gas flow, in particular a favorable swirl flow results.

Furthermore, it is conceivable that the holder 11 according to the 2a , d and e is designed as a grid and several wire knitted cushions 10 for supporting the particle filter 1 supports.

In addition, it is also conceivable that according to 2c a rectangular frame-shaped support zone 13 with points to the exit side 7 of the filter body 2 acting support segments 14 is combined and thereby a particularly favorable support of the filter body 2 can be achieved. The punctual support segments 14 are preferably at crossing points of the segment boundaries 12 arranged and guaranteed thereby. a uniform support of all adjacent filter segments 9 . 9 ' Etc.

In all embodiments, the at least one wire knitted cushion 10 preferably has a substantially rectangular configuration and is as well as the support frame 11 gas permeable.

According to 3 shows a detailed representation of the support of the filter body 2 or the individual filter segments 9 . 9 ' through the support frame 11 over the wire knitted pillow 10 , It can be seen that the holding frame 11 not directly on the output side 7 of the filter body 2 but over the wire mesh cushion 10 supported on this. The knitted wire pillow 10 is preferably at the filter segment boundary 12 arranged and thus supports several, here both, adjacent filter segments 9 and 9 ' evenly off. Because both the knitted wire pillow 10 as well as the support frame 11 are permeable to exhaust gases, a flow through the particulate filter 1 not or only marginally affected.

In summary, the essential features of the solution according to the invention can be characterized as follows:
The invention provides, in a particle filter 1 for an internal combustion engine, which at least one filter body 2 and one the filter body 2 surrounding jacket pipe 3 includes the filter body 2 at its exit 7 beab stands from its outer peripheral edge 8th axially on the casing pipe 3 and / or at the funnel 6 and / or on the output channel 5 support. In one of several filter segments 9 . 9 ' formed filter body 2 the support of the filter segments takes place 9 . 9 ' individually and / or in the area of a common filter segment boundary 12 , whereby slipping out of individual filter segments 9 . 9 ' from the filter body 12 can be avoided and also a flow cross section of the filter body 2 is not affected, since in the area of the filter segment boundaries 12 anyway no flow takes place.

It is particularly advantageous that the solution according to the invention in comparison to a conventional support via a support ring on the peripheral edge 8th of the filter body 2 avoids critical temperature stresses as a result of uneven flow and thereby prevents the formation of so-called ring-off cracks. In addition, a more uniform loading of soot particles and a uniform regeneration of the particulate filter 1 reached.

Claims (20)

Particle filter ( 1 ) for an internal combustion engine, in particular in a motor vehicle, comprising at least one filter body ( 2 ) and a filter body ( 2 ) surrounding jacket tube ( 3 ), - wherein the jacket tube ( 3 ) upstream in an input channel ( 4 ) and downstream in an output channel ( 5 ), - wherein the jacket tube ( 3 ) at least to the output channel ( 5 ) with a funnel ( 6 ), in particular concentric, tapered, - wherein the filter body ( 2 ) axially on the jacket tube ( 3 ) and / or at the funnel ( 6 ) and / or on the output channel ( 5 ) is supported, characterized in that the axial support of the filter body ( 2 ) on its output side ( 7 ) spaced from its outer peripheral edge ( 8th ) he follows. Particulate filter according to claim 1, characterized in that the filter body ( 2 ) of a plurality of monolithic filter segments ( 9 ) consists. Particulate filter according to claim 1 or 2, characterized in that the filter body ( 2 ) made of ceramic, in particular of silicon carbide or cordierite exists. Particulate filter according to one of claims 1 to 3, characterized in that the axial support with the aid of at least one Drahtgestrickkissens ( 10 ), which is on the output side ( 7 ) of the filter body ( 2 ) is present. Particulate filter according to claim 4, characterized in that the wire mesh cushion ( 10 ) substantially in the middle of the filter body ( 2 ) is arranged. Particulate filter according to claim 4 or 5, characterized in that the at least one wire knitted cushion ( 10 ) is formed so that at the output side ( 7 ) an annular or rectangular frame-shaped support zone ( 13 ) trains. Particulate filter according to one of claims 4 to 6, characterized in that the at least one wire knitted cushion ( 10 ) has a substantially rectangular configuration. Particle filter according to one of claims 4 to 7, characterized in that the wire mesh cushion ( 10 ) is gas permeable. Particulate filter according to one of claims 4 to 7, characterized in that in one of a plurality of filter segments ( 9 ) formed filter body ( 2 ) the at least one wire mesh cushion ( 10 ) is designed and arranged, that the at least one wire mesh cushion ( 10 ) almost all filter segments ( 9 ) is supported individually, and / or - that the at least one wire mesh cushion ( 10 ) at least two filter segments ( 9 ) in the area of a common filter segment boundary ( 12 ) is supported. Particle filter according to one of claims 4 to 9, characterized in that the wire mesh cushion ( 10 ) of a holding frame ( 11 ), which is located on the jacket tube ( 3 ) and / or at the funnel ( 6 ) and / or on the output channel ( 5 ) is supported. Particulate filter according to claim 10, characterized in that in one of a plurality of filter segments ( 9 ) formed filter body ( 2 ) the at least one wire mesh cushion ( 10 ) and the holding frame ( 11 ) is designed and arranged, that the at least one wire mesh cushion ( 10 ) almost all filter segments ( 9 ) is supported individually, and / or - that the at least one wire mesh cushion ( 10 ) at least two filter segments ( 9 ) in the area of a common filter segment boundary ( 12 ) is supported. Particulate filter according to claim 10 or 11, characterized in that the holding frame ( 11 ) is formed so that at the output side ( 7 ) an annular or rectangular frame-shaped support zone ( 13 ) trains. Particulate filter according to one of claims 10 to 12, characterized in that the holding frame ( 11 ) is gas permeable. Particulate filter according to one of claims 10 to 13, characterized in that the holding frame ( 11 ) several separate support segments ( 14 ), which on the jacket tube ( 3 ) and / or at the funnel ( 6 ) and / or on the output channel ( 5 ) are supported. Particulate filter according to claim 14, characterized in that the support segments ( 14 ) have a scoop-shaped cross section, such that during the flow through the particle filter ( 1 ) results in a defined exhaust gas flow, in particular a swirl flow. Particulate filter according to one of claims 10 to 15, characterized in that the holding frame ( 11 ) at the free end ( 15 ) of the filter body ( 2 ) extended output channel ( 5 ) is arranged. Particulate filter according to claim 16, characterized in that the output channel ( 5 ) on the extended section ( 16 ) is radially permeable to gas, in particular perforated or perforated, is. Particulate filter according to claim 16 or 17, characterized in that the extended section ( 16 ) of the output channel ( 5 ) Flow baffles ( 17 ), in particular dents and / or indentations, whereby a flow resistance within the extended section ( 16 ) is about as big as outside. Particulate filter according to one of claims 10 to 18, characterized in that the holding frame ( 11 ) is designed as a grid and several wire knitted cushions ( 10 ) for supporting the particulate filter ( 1 ) holds. Exhaust system for an internal combustion engine, in particular a diesel engine, with at least one particle filter ( 1 ) according to one of claims 1 to 19.