DE202012102041U1 - Particulate filter designed as a particulate filter - Google Patents

Abstract

Particulate filter designed as a particulate filter, such as soot particulate filter for removing soot particles from the exhaust stream of an internal combustion engine, comprising a filter housing in a housing (2) designed as a channel filter block unit (3) with a plurality of parallel through filter walls (7) separated, mutually closed end channels (6, 6.1), of which a first plurality on the upstream side and a further plurality is closed downstream, characterized in that the filter block unit (3) has a first, in the filter housing (2) upstream filter block (5) with channels in which only the channels (6.1) of the first plurality are closed at their upstream end, and a second, in the filter housing (2) the first filter block (5) in the flow direction of the exhaust gas downstream filter block (5.1) with channels (6), in which only the channels (6) of the second plurality at its downstream end versa are closed, that the first and the second filter block (5, 5.1) adjoin the front side and that starting from the end face of at least one of the two filter blocks (5, 5.1) in some of the two adjacent channels (6, 6.1) separating filter walls (7) recesses as bypass paths (9, 9.1) are introduced.

Description

The invention relates to a designed as a partial filter particulate filter, such as soot particulate filter for removing soot particles from the exhaust stream of an internal combustion engine, such as a diesel engine or a gasoline engine with direct injection, comprising a held in a filter housing, designed as a channel filter filter block unit with a plurality of parallel filter walls separated from each other , Mutually closed end channels, of which a first plurality on the upstream side and another plurality is sealed off downstream.

Such particulate filters are used, for example, for cleaning the exhaust gases of diesel engine-powered vehicles. With the aid of such filters, the soot particles entrained in the exhaust gas stream are filtered out of the exhaust gas stream. In addition to particle filters based on sintered metal, particle filters are also used whose filter block is made of a ceramic material. Such a filter block is designed in the manner of a channel filter and has a plurality of the longitudinal extension of the filter block of the following parallel channels, which are separated from one another by filter walls. The cross-sectional geometry of the channels can be square. Other cross-sectional geometries are also used. The filter channels of such a channel filter are alternately closed upstream or downstream. This means that the exhaust gas flowing into an outflow-sealed channel has to pass through the filter walls of this channel in order to pass into a channel open downstream of it. Thus, in such a filter, the filter walls form the filter medium. Due to the parallel arrangement of the alternately on or downstream open channels, these are sometimes addressed as a honeycomb filter.

In addition to particulate filters, in which all the exhaust gas must pass through the filter walls in each operating state of the filter, those which have one or more bypass paths are used. The one or more bypass pathways serve significantly the purpose that exhaust gas can pass through the particulate filter, even if this offers a relatively high exhaust backpressure due to a particularly high soot particulate loading. If the exhaust backpressure is too high, this impairs the operation of the internal combustion engine. Although such particulate filters are regenerated at intervals by inducing soot oxidation. However, a soot oxidation can not be performed in any operating condition of a motor vehicle. In such, also called Rußabbrand designated regeneration care must be taken to ensure that this is carried out as completely as possible, which in turn means that a sufficient time must be available, in which the engine is still in operation. Different strategies are known to determine the best possible time for such a Partikelfilterregneration and then trigger the regeneration process by supplying heat. It can therefore occur again and again situations in which although a regeneration of the particulate filter desired, but can not be triggered. In such cases, the bypass pathways ensure that the exhaust backpressure does not become too high despite the high particle filter load.

Even with regard to the legal limits, in many cases 100% filtering is not required. Tuning to the required rate of precipitation helps to reduce fuel consumption.

Different bypass solutions in the case of particle filters are known from the prior art. For example, in DE 10 2005 023 518 A1 a blockage-free filter unit described, are arranged in the filter block units in the flow direction at a distance one behind the other and there is a bypass guided around each filter block unit. In this way, there is a partial flow around the respective filter block unit.

In the case of ceramic filter blocks, filter-internal bypass is also realized. Ceramic filter blocks are produced with a base body with the filter walls by means of an extrusion process. In a subsequent step, the first continuous channels are mutually closed at their ends by inserting a sealing plug. To provide bypass pathways is off EP 1 408 208 B1 known to provide the downstream sealing plug with a through hole. In view of the fact that the cross section of the channels of such a ceramic honeycomb filter can only be about 1.5 mm, it is difficult to subsequently introduce this through opening into the sealing plugs. Moreover, there is a risk in the case of then necessarily only small through holes in the diameter that they clog even in the presence of smaller amounts of soot or ash and thus lose their effectiveness.

Out US 7,128,961 B2 a ceramic honeycomb filter is known in which some wall intersection points are not already formed during the extrusion of the base body. As a result, over the entire length of the filter there is a bypass pathway between two channels open on the inlet side and two channels open on the downstream side. In the case of the particle filter which has become known from this document, the bypass pathways in the production of the filter base body and thus in the Incorporated extrusion. As a result, such a filter body can not be manufactured with the usual tools. Moreover, in the concept known from this document, the effective flow cross-sectional area of such a bypass can be adjusted only with difficulty. The distance to be kept between otherwise adjacent filter walls would have to be kept very small in this concept so that the overall mobility of the over the entire length of the filter extending bypass is not too large.

Based on this discussed prior art, the invention has the object, a particulate filter mentioned above in such a way that the filter body can be prepared by conventional methods and thus standard and set up in a subsequent to the production of the ceramic body step Bypass pathways.

This object is achieved according to the invention by an aforementioned generic ceramic particle filter, in which the filter block unit a first, in the filter housing upstream filter block with channels, in which only the channels of the first plurality are closed at its upstream end, and a second, in the Filter housing has the first filter block in the flow direction of the exhaust gas downstream filter block with channels in which only the channels of the second plurality are closed at its downstream end, that the first and second filter block adjacent the front and that starting from the end face of at least one of the two filter blocks in some of the two adjacent channels separating filter walls recesses are introduced as bypass pathways.

In this particulate filter, the filter block unit is composed of two filter blocks. The two filter blocks each have a plurality of parallel channels. The special feature of the two filter blocks is that in the one filter block, a first plurality of filter channels on the inflow side and the other filter block, the second plurality of channels is closed downstream, thus these channels are each equipped with a sealing plug. The two filter blocks of the filter block unit are arranged in the filter housing to each other such that the filter block is arranged with the inflow-side closure body upstream of the other filter block in the filter housing. The second filter block is thus located in a downstream of the first filter block in the flow direction of the exhaust gas. In this are the corresponding plurality of channels closing plugs on the downstream side of this filter block. The two filter blocks adjoin each other with their facing end faces. Preferably, the pluralities of the channels of the two filter blocks are held in a mutually aligned arrangement in the filter housing, thus ultimately form in principle a known filter body with mutually inflow or outflow sealed channels. A special feature of the claimed particulate filter is that recesses are introduced into adjacent channels separating filter walls in the region of at least one of the two mutually facing end faces of the two filter blocks for forming the bypass pathway. These recesses extend from the respective end face opposite the side with the sealing plug and extend over a predefined length in the axial direction. These recesses in the filter walls form Querwegsamkeiten, through which flowing into the inflow-side open channels exhaust gas can flow directly into downstream open channels. In this way, bypass paths are formed, via which exhaust gas flowing into the particle filter can flow through it without having to penetrate through the filter walls.

The bypass pathways typically have such a cross-sectional area in their sum that, when the particulate filter is operated as intended, only part of the exhaust gas flowing into the filter body unit can pass through it unfiltered, for example up to 20%. In this way, it should not be ruled out that in the case of situations which occur only rarely in normal operation, for example in the case of excessive soot loading of the filter block unit or during operation of the internal combustion engine with only slight load or during idling, the major part or all of the exhaust gas will actually pass through the bypass Pathways streams.

The formation of the bypass pathway by providing recesses, starting at the end face of at least one of the two filter blocks allows a very accurate formation of the pathways and thus created flow cross-sectional area. This is achieved in that on the one hand, such a recess can extend over the entire cross-sectional area of a filter wall or even over only a part thereof. On the other hand, this is due to the fact that the flow-through cross-sectional area of such a bypass pathway is also defined by the axial extent of such pathway. Thus, in this embodiment, there are two variables on which the effective bypass pathway cross-sectional area can be set.

Of particular advantage in the subject of the particulate filter according to the invention is that the bypass paths later, that is: after a preparation of a conventional Filter block unit, can be formed. Thus, one and the same output filter block can be used to modify application-specific and without the actual manufacturing process, bypass paths with different cross-sectional area. The subsequent introduction of the recess can be done for example by drilling, milling or the like.

In addition, the uniform distribution of the exhaust gas flowing into the filter block unit can be taken into account in an application-specific manner with a subsequent introduction of the bypass paths. With an ideal uniform distribution of the exhaust gas flowing to the particle filter, the bypass pathways will be distributed uniformly over the cross-sectional area of the filter block. If the uniform distribution is not ideal, if desired, the bypass paths can be set up, for example, in those areas which carry fewer soot particles due to the unequal distribution. Depending on the desired destination, this can also be set up the other way round.

Depending on the design of the channel cross sections, the bypass paths may connect two or more, for example four adjacent channels, to one another.

According to a preferred embodiment, it is provided to produce a conventional filter block with mutually closed end channels in a first step. In a subsequent step, this filter block is divided transversely to form the two filter blocks according to the invention, for example in the region of the center. Thus, a first filter block with upstream closed channels of the first plurality of channels and a second block with downstream closed channels of the second plurality of channels are made. Above all, it is ensured in this embodiment that, in the case of a frontal adjacency of the two filter blocks, they can be brought into alignment with respect to their channels. In a preferred embodiment, the two filter blocks are aligned in the particle filter in such an arrangement to each other. In individual filter channels connecting pins can be used. With this concept, no tolerances have to be compensated, which must be taken into account when using two individually produced filter blocks. The splitting of a filter body produced, for example, with conventional process steps with end mutually closed channels, which is addressed in the context of these embodiments as manufacturing filter body to create the two required filter blocks also has the advantage that the division can be made in a manner that both Filter blocks fit together perfectly. Such an exact adjoining one another can also take place in such a way that the two end faces of the filter blocks catch each other transversely, as is typical, for example, in the case of fractured surfaces. Therefore, according to one embodiment, it is provided to divide a manufacturing filter body such that a fracture surface is provided at least over a partial cross-sectional area. This can also be achieved by oblique or curved division of a manufacturing filter body.

The claimed concept of forming the filter block unit by two filter blocks in the manner described also has the advantage that the application of a catalytic coating is simplified. Finally, only a plurality of the parallel channels is closed in the two filter blocks. In addition, it is possible to easily provide both filter blocks with a different catalytic coating. According to a further embodiment, it is provided that the filter block arranged upstream is catalytically coated on its upstream filter surface and the other filter is catalytically coated on its downstream filter surface.

The special particulate filter design also allows for another filter block to be located between the two filter blocks. However, this does not have closed-end channels. Rather, its channels serve to connect those of the first filter block with those of the downstream filter block. Nevertheless, in this example, the intermediate filter block has the opportunity to equip it with a different catalytic coating.

The two filter blocks are typically held with their facing end sides adjacent to each other in the filter housing, even with the interposition of a resilient compensation material, such as a wire mesh.

Further advantages and developments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. Show it:

1 FIG. 2 is a partial sectional view of a particulate filter according to an embodiment of the invention; FIG.

2 : a section of the filter block unit constructed from two filter blocks 1 in a longitudinal section,

3a . 3b FIG. 2: a perspective view of a section of the filter block arranged on the inflow side (FIG. 3a ) as well as the downstream side arranged filter block ( 3b ), which is shown enlarged relative to the first filter block and

4 An embodiment of the outflow-side arranged filter block according to another embodiment for providing bypass paths.

A particle filter 1 , intended for installation in the exhaust gas line of a diesel internal combustion engine, comprises one in a filter housing 2 accommodated and held therein filter block unit 3 , The filter block unit 3 is with the interposition of a storage mat 4 which in the illustrated embodiment consists of a wire mesh, in the filter housing 2 kept stationary. The filter block unit 3 The illustrated embodiment consists of two filter blocks 5 . 5.1 , The filter blocks 5 . 5.1 are made of a ceramic material as a honeycomb filter. As a result, it extends through the filter block unit 3 Following the longitudinal extension of a plurality of parallel channels (see 2 ). Adjacent channels are closed alternately upstream or downstream. The downstream sealed channels are denoted by the reference numeral 6 and the upstream sealed with the reference numeral 6.1 characterized. Separated are the channels 6 . 6.1 each other through a filter wall 7 , The cross-sectional geometry of the channels 6 . 6.1 is square, so every channel 6 . 6.1 of four filter walls 7 is enclosed. The filter walls 7 are used to filter the channels sealed in the downstream side 6 inflowing exhaust gas, if this through the filter walls 7 passes. Are then retained in the exhaust entrained particles, in particular soot particles, which successively on the upstream surface of the downstream sealed and upstream open channels 6 accumulate. The channels 6 . 6.1 are by means of sealing plugs 8th locked. Thus, in the filter block unit 3 the downstream closed channels 6 a first plurality and the upstream sealed channels 6.1 a second variety.

The filter block unit 3 consists of the two filter blocks 5 . 5.1 , which are arranged one behind the other in the flow direction and adjoin one another with their facing end faces. Held are the two filter blocks 5 . 5.1 in this contiguous arrangement through the enclosure in the storage mat 4 and the fitting in the filter housing 2 , Thus, it is with the two filter blocks 5 . 5.1 at least in the first instance to independent bodies, the first to the formation of the filter block unit 3 be brought into the arrangement shown to each other. In this arrangement, the longitudinal axial channels of the two filter blocks are aligned 5 . 5.1 together.

The filter block 5 includes, how out 2 recognizable, in a first plurality unclosed channels, namely the sub-channels of the channels 6 and a second plurality of channels sealed on the upstream side, namely parts of the channels 6.1 , At the filter block 5.1 is this the other way round? In this filter block 5.1 are the channel shares 6 sealed off downstream, while the shares of the channels 6.1 are open downstream.

The filter bodies have been produced 5 . 5.1 in a conventional manner by extruding a base body having the filter channels, in which in a subsequent step, the sealing plug 8th have been used alternately at opposite ends. This can also be done after the fire of the filter body. In a subsequent step, this manufacturing filter body is cut in the transverse direction to the two filter body 5 . 5.1 to create. As a result, the two filter body 5 . 5.1 frontally at the point of separation fit and with all channels aligned to each other.

Divided is the manufacturing body, so that starting from the end face of one of the two filter blocks Querströmwegsamkeiten can be set up to form a plurality of bypass pathways. In the illustrated embodiment, the device is at the rear in the flow direction of the exhaust gas filter block 5.1 at his to the filter block 5 pointing end face made. In this case, according to a predetermined grid starting from the to the filter block 5 facing end face of the filter block 5.1 Sections of filter walls separating two adjacent channels are removed to form recesses, for example by drilling or milling. In the three-dimensional representation of a section of the two filter bodies 5 . 5.1 this is recognizable. These bypass routes are indicated by the reference numeral 9 characterized. By removing discrete filter wall sections in this embodiment, in each case a downstream sealed channel 6 with a downstream open channel 6.1 connected. It is understood that the sum of the flow-through bypass pathways 9 not that big is that in the filter block unit 3 total incoming exhaust gas only via the bypass pathways 9 the filter block unit 3 could pass through. Rather, the cross-sectional area is the sum of the bypass pathways 9 so dimensioned that the remaining exhaust back pressure is still sufficiently large, so that at least up to a defined or definable filter loading into the filter block unit 3 inflowing exhaust gas majority of the filter walls 7 flows through.

4 shows a possible other embodiment for introducing bypass Pathways in a filter block. 4 shows as well as the 3b the downstream filter block in the flow direction 5.2 in a view of its facing the direction upstream of the filter block face. Unlike the filter block 5.1 are with this filter block 5.2 the bypass pathways 9.1 introduced at the intersections of filter walls. In this way, two downstream filter channels are connected to two outflow-side open filter channels.

How special from the 3b and 4 has an influence on the assessment of the effectiveness of the bypass pathways 9 . 9.1 not only the axial extent of the same extent forming recesses in the filter walls 7 but also the extension of such a recess in the transverse plane.

In addition to the above-described measures can be provided, the two frontally adjacent filter blocks 5 . 5.1 to arrange with a small gap to each other, if a correspondingly greater bypass-Wegsamkeit to be created.

In the exemplary embodiments, the bypass pathways in the flow direction in the rear filter block have been introduced from its pointing to the other filter block face. It is understood that these can also be introduced into the end face of the first filter block pointing to the rear filter block or both.

In the illustrated embodiment, the downstream filter block is in the flow direction 5.1 shorter than the first filter block 5 , This too is to be understood as an example. A division of a manufacturing filter block is also possible elsewhere, for example in the middle without further ado for the realization of the invention.

The design of the filter block unit with at least two filter blocks also has a positive effect with respect to thermal stresses. As a result of this concept, the length of the individual filter body is correspondingly short, in particular shorter than the length of a conventionally manufactured in one piece filter block unit. Different thermal effects on the two filter blocks do not necessarily result in stresses in the other filter block due to loose contiguousness.

LIST OF REFERENCE NUMBERS

1

 particulate Filter

2

 filter housing

3

 Filters block unit

4

 positioning mat

5, 5.1, 5.2

 filter block

6, 6.1

 channel

7

 filter wall

8th

 sealing plug

9, 9.1

 Bypass passage means

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005023518 A1 [0005]
• EP 1408208 B1 [0006]
• US 7128961 B2 [0007]

Claims (12)

Particulate filter designed as a particulate filter, such as soot particle filter for removing soot particles from the exhaust stream of an internal combustion engine, comprising a filter housing in a ( 2 ), designed as a channel filter filter block unit ( 3 ) with a plurality of parallel through filter walls ( 7 ) of mutually separate, mutually closed end channels ( 6 . 6.1 ), of which a first plurality upstream and a further plurality is closed downstream, characterized in that the filter block unit ( 3 ) a first, in the filter housing ( 2 ) upstream filter block ( 5 ) with channels where only the channels ( 6.1 ) of the first plurality are closed at their upstream end, and a second, in the filter housing ( 2 ) the first filter block ( 5 ) in the flow direction of the exhaust gas downstream filter block ( 5.1 ) with channels ( 6 ), in which only the channels ( 6 ) of the second plurality are closed at their downstream end, that the first and the second filter block ( 5 . 5.1 ) border on the front side and that starting from the end face of at least one of the two filter blocks ( 5 . 5.1 ) into some of the two adjacent channels ( 6 . 6.1 ) separating filter walls ( 7 ) Recesses as bypass paths ( 9 . 9.1 ) are introduced. Particulate filter according to claim 1, characterized in that the recesses ( 9.1 ) in the region of the crossing points of the filter walls ( 7 ) are arranged and thus the forming of such a crossing point filter walls ( 7 ) limited channels ( 6 . 6.1 ) are interconnected. Particulate filter according to claim 1 or 2, characterized in that the channels ( 6 . 6.1 ) of the two filter blocks ( 5 . 5.1 ) are arranged in alignment with each other. Particulate filter according to one of claims 1 to 3, characterized in that the two filter blocks ( 5 . 5.1 ) by dividing one with mutually closed channels ( 6 . 6.1 ) produced filter block are created. Particulate filter according to claim 4, characterized in that the two end faces of the filter blocks ( 5 . 5.1 ) fit together exactly. Particulate filter according to claim 5, characterized in that the two adjoining end faces of the two filter blocks ( 5 . 5.1 ) have complementary fracture structures at least in a partial area. Particulate filter according to one of claims 1 to 6, characterized in that the two filter blocks ( 5 . 5.1 ) with the interposition of a heat-resistant compensating material, such as a storage mat ( 4 ), in the filter housing ( 2 ) are held. Particulate filter according to one of claims 1 to 7, characterized in that at least one of the two filter blocks ( 5 . 5.1 ) is catalytically coated. Particulate filter according to claim 8, characterized in that the two filter blocks ( 5 . 5.1 ) have a different catalytic coating. Particle filter according to claim 8 or 9, characterized in that the inflow side arranged filter block are catalytically coated on its upstream filter surface and the second filter body on its downstream filter surface. Particulate filter according to one of claims 1, 2, 7, 8, 9 or 10, characterized in that the two filter blocks are offset from each other by an angular amount about the longitudinal axis of the filter block unit. Particulate filter according to one of claims 1 to 4 or 7 to 11, characterized in that the two filter blocks of the filter block unit are spaced from each other. Particulate filter according to claim 12, characterized in that between the two filter blocks of the filter block unit, a further element is switched on for the purpose of exhaust gas purification.

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