DE102017103555A1 - Particulate filter for an internal combustion engine with a catalytically active coating - Google Patents

Abstract

A particulate filter (10) for an internal combustion engine having a catalytically active coating (28) for purifying an exhaust gas (22), the particulate filter (10) being crossed by a plurality of channels (12, 14) which are in contact with the catalytically active coating (28). 28) are at least partially provided and mutually closed, and wherein the channel walls (18) for the passage of the exhaust gas through the channel walls (18) of the inlet side (20) open channels (12) in the outlet side (24) open channels (14) porous It is proposed that the channels (12) open to the entry side (20) be provided at the closed ends over a predetermined length (l.), providing a need-based use of washcoat and precious metals, and therefore reducing their consumption compared to the prior art ) are filled and / or the channels (14) open at the outlet end (24) are filled at the closed ends over a predetermined length (1) d, whereby in each case a free length (l, l) of the channels (12, 14) results and in the region in which the free length (l) of the inlet side (20) open channels (12) with the free length (l ) which intersects the outlet side (24) open channels (14), a passage region (26) in the channel walls (18) for the exhaust gas (22) is arranged.).

Description

The invention relates to a particulate filter for an internal combustion engine having a catalytically active coating for purifying an exhaust gas, wherein the particulate filter is crossed by a plurality of channels, which are at least partially provided with the catalytically active coating and mutually closed, and wherein the channel walls for the passage of Exhaust gases are porous through the channel walls of channels open to the inlet side in open channels to the outlet side.

Particulate filters are used for exhaust aftertreatment of petrol and diesel internal combustion engines in order to reduce their particle emission. A particulate filter is usually based on a filter body provided with channels in the flow direction, wherein the channels are mutually closed and the channel walls have a predetermined porosity. Due to the mutual closure of the channels, a wall passage of the exhaust gas flowing through the filter body is forced, as a result of which particles located in the exhaust gas are filtered out of the exhaust gas. The channel walls can also be provided with a coating which contains a noble metal-containing catalyst material for further exhaust gas treatment. The catalytically active coating is applied as a so-called "washcoat".

The mutually sealed channels extend parallel over the entire length of the channel corresponding to the length of the filter body, and the exact range at which the exhaust gas passes from one channel through the channel wall to the other channel open on the outlet side can not be determined unambiguously , Therefore, all channels are largely provided with the noble metal-containing coating to ensure sufficient contact of the exhaust gas with the coating. However, this means that more washcoat and precious metal are used than is actually necessary.

In the DE 10 2000 051 020 A1 a particle filter for exhaust gas purification of a diesel engine is described, the channels are mutually closed.

Individual channels are partially filled with a filler material to reduce thermal stresses during operation of the filter by locally adjusting the heat capacity of the filter. As a result, the flow through the exhaust gas channel length is varied.

From the EP 1 484 482 A1 is a catalytically active particulate filter with a so-called honeycomb structure known whose channels are mutually closed. In order to prevent the relatively thin ceramic material of the particulate filter flaking off during transport and handling or the closed channels open due to mechanical stress, it is provided to vary the closure length of the vulnerable channels. Thus, the shutter length may decrease from the edge of the particulate filter to the center thereof.

The invention has for its object to provide a particle filter with a noble metal-containing coating that allows a needs-based use of washcoat and precious metals.

The object is achieved by a particle filter according to claim 1. Preferred embodiments of the invention are subject of the dependent claims.

According to the invention, a particulate filter for an internal combustion engine with a catalytically active coating for purifying an exhaust gas is provided, wherein the particulate filter is traversed by a multiplicity of channels which are at least partially provided with the catalytically active coating (washcoat) and mutually closed. The channel walls are porous to the passage of the exhaust gas through the channel walls open to the inlet side channels in the outlet side open channels, wherein the channels open to the inlet side are filled at the closed ends over a predetermined length and / or open to the outlet side channels at the closed ends are filled over a predetermined length, which in each case results in a free length of the channels and in the region in which the free length of the channels open to the inlet side overlaps with the free length of the channels open to the outlet side, arranged a passage area in the channel walls for the exhaust gas is.

The free length of the channels open to the inlet side and the channels open to the outlet side may either be the same or different. Accordingly, the passage area in the exhaust gas passage walls may be centrally located in the particulate filter, between the center of the particulate filter and the exhaust gas entrance side or between the center of the particulate filter and the exhaust gas outlet side.

The free length of all open to the inlet side channels is always the same and the free length of all the channels open to the exit side is always the same.

Due to the arrangement and length of the passage area can be advantageously taken advantage of a thermal load of the particulate filter.

The length of the passage region is preferably between 10 and 80%, more preferably between 15 and 60% and most preferably between 20 and 30% of the total length of the particulate filter. Over the length of the passage region can advantageously also the amount of particles that can be stored maximally be determined. In addition, it can influence the pressure conditions in the particle filter.

The free length of the channels is determined by plugs used to close the channels and how far they extend into the channels. Alternatively, the channels may also be varied in length with a filler material in conjunction with a plug. Furthermore, other configurations for varying the channel length are possible.

The particle filter consists of the materials known to those skilled in the art. The particle filter is preferably made of a ceramic material or metal and particularly preferably of a ceramic material, wherein the pores of the channel walls are preferably 5-50 μm, more preferably 18-22 μm.

The catalytically active coating (washcoat) can be realized in such a way that it is applied to the channel walls, wherein a certain depth of penetration into the channel walls can be given or that it is completely introduced into the channel walls, whereby the cross section of the channel walls is not reduced ,

The coating may be provided at the channels open to the inlet side and / or at the channels open at the outlet side. Even a partial coating of the corresponding channels is provided according to the invention.

Since in the particulate filter according to the invention is advantageously known, where the passage of the exhaust gas takes place, in order to keep the back pressure of the particulate filter as low as possible, a coating may be provided only on one side of the passage area. Also, in this area, a coating can be completely eliminated if otherwise sufficient coating is present in the channels.

At least one catalytically active material selected from the following group is preferably provided for the particle filter according to the invention and, accordingly, for the coating: platinum, palladium, rhodium, barium and zeolite, particularly preferably platinum, palladium and rhodium.

The particulate filter according to the invention can be advantageously designed for use with a gasoline or diesel internal combustion engine.

Advantageously, can be significantly reduced by the inventive design of a particulate filter, the amount of precious metal needed because the passage area of the exhaust gas is precisely defined by the channel walls and thus only the actually required amount of catalytic coating must be used.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

• 1 in einer geschnittenen Detailansicht zwei wechselseitig verschlossene Kanäle eines Partikelfilters nach dem Stand der Technik,
• 2 in einer geschnittenen Detailansicht zwei wechselseitig verschlossene Kanäle eines erfindungsgemäßen Partikelfilters ohne Darstellung der Beschichtung,
• 3 in einer geschnittenen Detailansicht die zwei wechselseitig verschlossenen Kanäle des erfindungsgemäßen Partikelfilters nach 2 mit abweichender Abgasführung, und
• 4 in einer geschnittenen Detailansicht zwei wechselseitig verschlossene Kanäle eines erfindungsgemäßen Partikelfilters nach einer zweiten Ausführungsform mit Darstellung der Beschichtung.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

• 1 in a sectional detail view two mutually closed channels of a particle filter according to the prior art,
• 2 in a sectional detail view two mutually closed channels of a particle filter according to the invention without showing the coating,
• 3 in a sectional detail view of the two mutually closed channels of the particle filter according to the invention after 2 with deviating exhaust system, and
• 4 in a sectional detail view of two mutually closed channels of a particulate filter according to the invention according to a second embodiment with representation of the coating.

1 shows a detail of a particulate filter 10 According to the state of the art. The particle filter 10 has a variety of channels 12 . 14 on, of which here only two mutually by plug 16 closed channels 12 . 14 are shown. The channels 12 . 14 are separated from each other by porous channel walls 18 separated. There are channels 12 given that to the entry side 20 an exhaust gas, symbolized by arrows 22 , are open, and channels 14 leading to the exit side 24 of the exhaust gas 22 are open. That in the on the entry side 20 open channel 12 incoming exhaust gas 22 is through the channel 12 until the stopper 16 directed. The exhaust gas occurs 22 through the porous canal walls 18 in neighboring channels 14 , where in 1 only the passage to the one channel shown 14 will be shown. Subsequently, the exhaust gas leaves 22 the exit side 24 open channel 14 , The passage of the exhaust gas can theoretically over almost the entire length l _ges of the particulate filter 10 respectively. In the field of plugs 16 is of course no passage of the exhaust gas 22 through the canal wall 18 possible. Therefore, the passage area corresponds 26 almost the entire length l _ges of the particulate filter 10 so that both channels 12 . 14 over almost the entire length l _ges are provided with a catalytically active coating, not shown here, to ensure sufficient contact of the exhaust gas with the coating.

In the following 2 to 4 be embodiments of the particulate filter according to the invention 10 illustrated, wherein for like features the same reference numerals are used as in 1 , A catalytically active coating is only available in 4 shown.

In the 2 and 3 In each case, the same embodiment of the particulate filter according to the invention is shown in detail view 10 illustrated, however, wherein the flow direction of the exhaust gas 22 in both 2 and 3 is opposite.

In 2 the exhaust gas occurs 22 in the particle filter 10 on the to the entrance side 20 open channel 12 one that has a free length l _Free of the canal 12 which is less than the length l _ges of the particulate filter 10 , The other channel 14 , the exit side 24 is open, however, has a significantly shortened free length l _Afrei on, being in the area where the free lengths l _Free . l _Afrei both channels 12 . 14 overlap, the passage area 26 with the length l _D is arranged. The plugs 16 of the channels 12 . 14 each have a length l _Efüll , l _filling which differ from each other and, accordingly, also the free lengths l _Efre , l _{Afrei i of} the channels 12 . 14 , By appropriate dimensioning of the plug 16 and thus the free lengths l _Efre , l _Afrei of the channels 12 . 14 becomes the length l _D of the passage area 26 in the canal wall 18 Are defined. The arrangement of the area 26 for the passage of the exhaust gas 22 does not have to be done in the manner shown. This can also be in the middle of the particulate filter 10 or to the entrance page 20 to be relocated. The 2 and 3 differ only in the flow direction of the exhaust gas 22 so that the free lengths l _Efre , l _Afrei both channels 12 . 14 is opposite in both figures.

4 corresponds again 2 with respect to the flow direction of the exhaust gas 22 , Otherwise is in 4 a catalytically active coating 28 the canal walls 18 the two channels 12 . 14 shown, for simplicity, this only in the between the two channels shown 12 . 14 located channel wall 18 is shown. Usually, the channel walls 18 on all sides with a coating 28 Mistake. The coating 28 is partially on the surface of the channel wall 18 and has partially penetrated into this. In the passage area 26 is the coating 26 only on the side of the exit side 24 open channel 14 also shown otherwise with the coating 26 is provided.

LIST OF REFERENCE NUMBERS

10

particulate Filter

12, 14

channel

16

Plug

18

channel wall

20

entry page

22

Gas / arrow

24

exit side

26

Passage region

28

catalytic coating

l _ges

Length of the entire particle filter

l _filling

Length of the filled channel

l _filling

Length of the filled channel

l _Free

free length

l _Afrei

free length

l _D

Length of the passage area

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 102000051020 A1 [0004]
• EP 1484482 A1 [0006]

Claims (10)

Particulate filter (10) for an internal combustion engine with a catalytically active coating (28) for cleaning an exhaust gas (22), wherein the particulate filter (10) is crossed by a plurality of channels (12, 14) which are in contact with the catalytically active coating (28 ) are at least partially provided and mutually closed, and wherein the channel walls (18) for the passage of the exhaust gas through the channel walls (18) of the inlet side (20) open channels (12) in the outlet side (24) open channels (14) are porous , characterized in that the channels (12) open to the entry side (20) are filled at the closed ends over a predetermined length (1 _filling ) and / or the channels (14) open at the outlet ends (24) at the closed ends predetermined length (l _filling ) are filled, whereby in each case a free length (l _{E free} , l _{A free} ) of the channels (12, 14) results and in the area in which the free length (l _Efrei ) of the Entry side (20) open channels (12) with the free length (l _Afrei ) of the outlet side (24) open channels (14) intersects, a passage region (26) in the channel walls (18) for the exhaust gas (22) is arranged. Particle filter (10) after Claim 1 , characterized in that the free length (l _{E free} ) of the inlet side (20) open channels (12) differs from the free length (l _{A free} ) to the outlet side (24) open channels (14). Particle filter (10) after Claim 1 or 2 , characterized in that the channel walls (18) of the channels (12) open to the inlet side (20) and / or the channel walls (18) of the channels (14) open to the outlet side (24) at least partially communicate with the catalytically active coating (28). are provided. Particle filter (10) according to one of Claims 1 to 3 , characterized in that the passage region (26) is arranged centrally in the particle filter (10) or between the center of the particle filter (10) and the inlet side (20) or between the center of the particle filter (10) and the outlet side (24). Particle filter (10) according to one of Claims 1 to 4 , characterized in that the channels (12, 14) are closed by plugs (16), optionally in connection with a filling material and reduced in the free length (l _free ). Particle filter (10) according to one of Claims 1 to 5 , characterized in that the length (l _D ) of the passage region (26) between 10 and 80%, preferably between 15 and 60% and particularly preferably between 20 and 30% of the total length (l _ges ) of the particulate filter (10). Particle filter (10) according to one of Claims 1 to 6 , characterized in that the passage region (26) is not provided on one or both sides, preferably not or on one side with a catalytic coating (28). Particle filter (10) according to one of Claims 1 to 7 , characterized in that the catalytically active coating (28) contains at least one catalytically active material from the following group: platinum, palladium, rhodium, barium and / or zeolite. Particle filter (10) according to one of Claims 1 to 8th , characterized in that the pores of the channel walls (18) are 5 - 50 microns, preferably 18 - 22 microns in size. Particle filter (10) according to one of Claims 1 to 9 , characterized in that the particulate filter (10) is adapted to clean the exhaust gas of a gasoline or diesel internal combustion engine.

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