DE10359574A1 - Particle filter for cleaning exhaust gases - Google Patents

Abstract

The invention relates to a particle filter for cleaning exhaust gases of self-igniting internal combustion engines, the filter bags (5), which are positively connected at one end face with an outer retaining ring (2). The filter pockets (5) are arranged rotated in an angle (9) to the radial direction (8) such that a longitudinal expansion (7) of the filter pockets (5) in the radial direction to a movement (10) of the inner retaining ring (3) in tangential Direction leads.

Description

technical area

in the Exhaust gas in particular of internal combustion engines with inhomogeneous Mixture formation are soot particles contain. These soot particles can to injury to lead the health. For this reason, it is necessary to remove the soot particles from the exhaust gas remove. This is done through the use of particulate filters, which are arranged in the exhaust system of the motor vehicle.

particulate Filter, for example, as used in the prior art include individual Channels, which are closed on one side. This must be on the open Side in the channels incoming Flue gas through the filter material. The pores in the filter material are dimensioned so that the particles are retained and adsorb on the filter material. From EP-A-1 256 369 For example, an exhaust filter is known in which by a folded Filter medium is formed a plurality of axial channels. The channels are each closed on one side. A compact design is characterized achieved that the folded filter medium is wound up. Of the wrapped filter is housed in a housing so that the outside flush with the filter on the housing wall is applied.

A additional design for Particulate filter is known from DE-C-36 37 516. This patent describes filter elements for Dust filters, which are located in a separating floor between the dust gas and the clean gas side are fixed and of one with dust gas entry, clean gas discharge and Staubgasaustrag provided housing are surrounded. The filter elements are flows through from the gases to be cleaned from outside to inside. The filtering outer surface of the Filter element is made of wedge-shaped extending, juxtaposed to the central axis of the filter element cells designed, which are similar to a tube at its upper end and at its lower end star-shaped converge on a midline that points toward the individual Cell bisector is arranged.

One For example, filter filters made of filter bags are made WO 02/102494 A1. Here are filter surfaces made of sintered metal Filter bags designed in a wedge shape, the blunt wedge end a pocket opening is assigned. The wedge surfaces as sidewalls the filter bags run against the opposite of the pocket opening Wedge ends and one of the wedge flanks running between the wedge ends each in a wedge cutting. This results in relation to the Flow direction of the particulate filter on one side through adjacent filter bags against each other delimited, large wedge areas. On the other side the above filter surfaces be streamed Wedge interior via pocket openings a large exit the gases.

At the Operation of the particle filter for exhaust gas purification of motor vehicles the filter elements settle over time due to the filtered soot to. This increases the flow resistance of the filter, which adversely affects the performance and fuel economy the internal combustion engine effects. For this reason, the Filter elements cleaned regularly become. This is done by heating, causing the adsorbed soot burn.

By the high temperatures that occur during cleaning stretch the filter elements. So by the strong heating of the filter bags no additional tensions during regeneration occur, the end, which is opposite to the housing-mounted side, not with the case connected. The individual filter bags are connected only by a support ring. in the ongoing operation of the motor vehicle, the particulate filter to Vibrations are stimulated. This can lead to an additional high load at the joints come.

One Particulate filter, as used in the prior art, includes filter bags that come with an inner retaining ring and an outer retaining ring are connected. The filter bags have side walls made of sintered metal are. For purifying the exhaust gas of internal combustion engines, the exhaust gas flows through the side walls Sintered metal. In this case, the particles contained in the exhaust gas, predominantly soot particles, from the porous ones sidewalls retained.

Around one possible size filter area in a particular housing To realize, the filter bags are arranged in a star shape. Here are the run side walls the filter pockets radially from the inner retaining ring to the outer retaining ring.

at known from the prior art particulate filters have the Filter bags have an open face through which the exhaust usually passes flows.

The individual filter bags are on the exit side with the outer retaining ring and the inner retaining ring connected. The connection is preferably made by welding.

The connection between the outer retaining ring and the filter pockets must be tight throughout the life of the particulate filter ensure that the exhaust gas flows through the porous sintered metal sidewalls.

by virtue of the withheld during operation Particle settles the particle filter over time. Both Particles are preferably soot. To the Flow resistance of the Particle filter as possible keep low, the soot deposits be removed from time to time. This is preferably done by a thermal regeneration. Here, the particulate filter on a brought so high temperature that the soot particles burn. These high temperatures cause that the filter pockets in both the axial and in radial Strengthen direction strongly.

by virtue of the elongation The filter bags in the radial direction occur stresses on the welds of the Filter pockets on the outer retaining ring on. These voltages lead causing cracks during the operating time of the particulate filter form at the welds. The cause of the cracking can be seen in the fact that the outer retaining ring less expands than the filter bags.

The Cracks lead first to that the connection of the filter bags with the outer retaining ring becomes unstable, further, exhaust gas can flow through the cracks and is therefore no longer cleaned by contained particles.

presentation the invention

One formed according to the invention Particle filter for cleaning exhaust gases from internal combustion engines includes filter bags which are positively connected with one end face an outer retaining ring and an inner retaining ring are connected. The filter bags are like that rotated at an angle of preferably more than 10 ° to the radial position arranged that a longitudinal strain the filter pockets in the radial direction to a movement of the inner Retaining rings in the tangential direction leads. This twists the inner retaining ring until the elongation of the filter pockets is balanced.

In a preferred embodiment of the particulate filter, the filter bags are made of sintered metal. Hereby flows the exhaust gas through porous walls Sintered metal, wherein particles contained in the exhaust gas are deposited on the sintered metal walls. The sintered metal walls are preferably made of a wire mesh, which has an open Cross-section of more than 60%. On the wire mesh is a sintered metal layer is applied to the wire mesh is sintered together.

The Filter bags are preferably welded to the outer retaining ring. hereby becomes a gas-tight connection between the individual filter bags and the outer retaining ring reached. The gas-tight connection between the filter bags and the outer retaining ring is required so that the entire exhaust gas through the sintered metal walls of the Filter bags flows.

In a preferred embodiment is the inventively designed Particle filter in a housing attached. The fixation of the particulate filter in the housing takes place preferably by a screw connection of the outer retaining ring with the housing.

The from the inner retaining ring to the outer retaining ring extending side walls the filter bag can be executed either straight or curved. For currently running sidewalls have the filter bags a triangular Cross-section, executed at bent sidewalls The filter bags have a crescent-shaped cross-section.

drawing

in the Following, the invention will be described with reference to a drawing.

It shows:

1.1 a plan view of the outflow side of a manufactured according to the prior art particulate filter,

1.2 a plan view of the outflow side of an inventively designed particulate filter with straight side walls of the filter bags,

2 a top view of a section of the inflow side of an inventively designed particulate filter with curved side walls of the filter bags,

3 a section through a particle filter with housing,

4 a perspective view of a filter bag.

variants

1.1 a plan view is to be taken on the outflow side of a manufactured according to the prior art particulate filter.

A particle filter 1 includes filter bags 5 attached to one end with an outer retaining ring 2 , which is preferably designed as a flange, and an inner retaining ring 3 are connected. Preferably on the front side, with which the filter bags 5 with the outer retaining ring 2 and the inner retaining ring 3 connected are the filter bags 5 open. These are in the filter bags 5 each spacer plates 8th received, which are preferably formed in the form of a corrugated sheet.

The connection of the filter bags 5 with the outer retaining ring 2 and the inner retaining ring 3 preferably takes place positively, for example by welding.

The filter bags 5 have sidewalls 6 , which are preferably made of a sintered metal. The sintered metal is a porous material through which the exhaust gas of the internal combustion engines flows. For the production of the side walls 6 Preferably, a high-temperature-resistant wire mesh having an open cross section of more than 60% is used, on which a high temperature-resistant, porous sintered metal layer is applied and sintered together with the wire mesh. The pore size of the sidewalls 6 made of sintered metal is chosen so that contained in the exhaust gas particles, especially soot particles, are recorded. As a result, the exhaust gas is purified by the particles contained therein.

The particle filter 1 is preferably in an in 1.1 Housing not shown received. The connection of the particle filter 1 with the housing is preferably non-positively via the flange formed as an outer retaining ring 2 , For this purpose, in a preferred embodiment in the outer retaining ring 2 drilling 4 attached, through which the particle filter 1 is bolted to the housing.

Through the from the side walls 6 The particle filter is retained by particles retained by porous sintered metal 1 in the course of operation too. For this reason, the particle filter must 1 be cleaned at regular intervals. The cleaning of the particles is preferably carried out thermally at high temperatures. As a result, the retained soot particles burn. The high temperatures occurring during the thermal regeneration lead to a length expansion 7 the side walls 6 the filter bags 5 , Because of the outer retaining ring 2 is screwed to the housing, not shown here and so has contact with the environment, to the heat from the outer retaining ring 2 and is discharged from the housing, heats the outer retaining ring 2 less strong than the filter bags 5 , This is the extension of the filter bags 5 greater than the elongation of the outer retaining ring 2 , which causes at the joints, with which the filter bags 5 with the outer retaining ring 2 are connected, voltages occur.

Also during operation is the outer retaining ring 2 colder than the filter bags 5 , causing the filter bags 5 have a greater thermal expansion than the outer retaining ring 2 ,

The different thermal expansions of the filter bags 5 and the outer retaining ring 2 lead to tensions at the joints between the filter bags 5 and the outer retaining ring 2 which may result in cracking. Cracks between the filter bags 5 and the outer retaining ring 2 cause exhaust gas to flow directly over the cracks and not through the filter bags 5 , This leads to a reduction of the cleaning performance of the particulate filter 1 , because not all the exhaust gas through the filter bags 5 flows and thus the exhaust gas is only partially or not cleaned at all.

1.2 shows a plan view of the outflow side of an inventively designed particulate filter with straight side walls of the filter bags.

To reduce the on the junction of the filter bags 5 with the outer retaining ring 2 acting stresses are in the inventively designed particulate filter 1 the filter bags 5 at an angle 9 twisted to the radial direction. The angle 9 is preferably greater than 10 °.

By twisting the filter bags 5 around the angle 9 leads the elongation 7 the side walls 6 the filter bags 5 due to the heating and the thermal expansion caused thereby, to the inner retaining ring 3 one with the reference numeral 10 marked movement is impressed in the tangential direction. This twists the inner retaining ring 3 until the elongation 7 the side walls 6 the filter bags 5 is balanced. The movement 10 of the inner retaining ring 3 in the tangential direction causes at the welds, with which the filter bags 5 on the outer retaining ring 2 are attached, no tensions occur and thus cracking is avoided. This will increase the life of the particulate filter 1 elevated. An enlargement of the angle 9 leads to an improved implementation of the elongation 7 into the movement 10 of the inner retaining ring 3 in tangential direction. Once the filter bags 5 cool down and allow the side walls 6 shorten again, also turns the inner retaining ring 3 back to the starting position.

A like in 1.2 shown, rotated to the radial position in a clockwise direction arrangement of the filter bags 5 leads to a longitudinal expansion 7 the side walls 6 the filter bags 5 to a movement 10 of the inner retaining ring 3 against the Clockwise to the elongation 7 compensate. An anti-clockwise direction to the radial position twisted arrangement of the filter bags 5 on the other hand leads to a movement 10 of the inner retaining ring 3 in a clockwise direction due to thermal expansion when heating the filter bags 5 occurring elongation 7 the side walls 6 compensate.

Another advantage, which is due to the angle 9 twisted arrangement of the filter bags 5 results, is that at the same size of the outer retaining ring 2 and the inner retaining ring 3 As in the known from the prior art arrangement with radially arranged filter pockets, the filter area is increased at a constant filter volume.

In 2 is a section of a plan view of the upstream side of an inventively designed particulate filter shown with curved side walls of the filter bags.

In addition to the in 1.2 illustrated embodiment with straight side walls 6 the filter bags 5 can the filter bags 5 also curved sidewalls 11 to have. Even with curved side walls 11 leads a length expansion 7 the side walls 11 to a movement 10 of the inner retaining ring 3 in tangential direction until the elongation 7 is balanced, reducing the tension on the connection of the filter bags 5 with the outer retaining ring 2 be reduced. Another advantage of the curved side walls 11 is to be seen in that opposite straight sidewalls 6 at the same diameter of the inner retaining ring 3 and the outer retaining ring 2 the filter area is further increased.

On the upstream side are the filter bags 5 closed. This ensures that the exhaust gas through the side walls 11 the filter bags 5 has to flow. The closing of the filter bags 5 on the inflow side is preferably carried out by roll welding. For this purpose, first a side wall 11 . 6 around the other side wall 11 . 6 the filter bag 5 folded. Then the side walls become 6 . 11 at the fold 12 welded together.

On the to a cavity 15 inside the particulate filter 1 assigning side are the filter bags 5 at a junction 14 also closed. The connection point 14 is also preferably produced by roll welding. Again, a side wall 11 . 6 the filter bag 5 around the other side wall 11 . 6 the filter bag 5 folded and then welded.

So between the individual filter bags 5 on the outflow side, no exhaust gas can flow through, are the filter bags 5 on the outflow side along the side walls 11 . 6 connected with each other. The connection is denoted by the reference numeral 13 characterized. Again, a tight connection of the individual filter bags 5 preferably obtained by welding together.

On the upstream side are the filter bags 5 through a support ring 16 standing on the outside of the filter bags 5 running along, held in place.

3 shows a section through an inventively designed particulate filter with housing.

The particle filter 1 is in a housing 19 received, through which flows the exhaust gas generated by the internal combustion engine. The direction of flow of the particulate filter is indicated by the arrow 17 characterized. The exhaust gas reaches the outer sides of the side walls 11 . 6 the filter bags 5 , flows through the side walls 6 . 11 , whereby it is cleaned of particles contained in the exhaust gas and occurs at the outer retaining ring 2 facing side again from the filter bags 5 out. The outflow direction of the exhaust gas from the housing 19 is with the arrow 18 characterized.

To the particle filter 1 in the case 19 to be able to mount is on the housing 19 a flange 21 educated. The housing 19 comes with a housing cover 20 closed, on which a flange 22 is trained. The flange 21 of the housing 19 , the outer retaining ring 2 of the particulate filter 1 and the flange 22 of the housing cover 20 be along the holes 3 screwed together. Preferably located between the flange 21 and the outer retaining ring 2 and the outer retaining ring 2 and the flange 22 Sealing rings. This ensures that no exhaust gas at the connection between the housing 19 , Particle filter 1 and housing cover 20 can escape.

So no exhaust gas through the cavity 15 can escape without over the filter bags 5 Being directed is the cavity 15 on the outflow side through the inner retaining ring 3 locked.

A perspective view of a single filter bag is in 4 shown.

A filter bag 5 is on the upstream side here by the direction of flow 17 marked, on the side facing the filter center and on the outside 23 locked. On the outflow side, here by the outflow direction 18 marked, is the filter bag 5 open. This results in filter bags 5 with straight side walls 6 a triangular cross-section on the outflow side. For filter bags with curved side walls 11 the cross section at the outflow side is sickle-shaped.

The outside 23 the filter bag 5 is also triangular. To the filter bag 5 is open in the filter bag 5 a spacer plate 8th added. The spacer plate 8th is preferably formed in the form of a corrugated sheet. In a preferred embodiment, the filter bag 5 made of a high temperature resistant wire mesh with an open cross section of preferably more than 60%. On the wire mesh, a high temperature sintered metal layer is applied, which is sintered together with the wire mesh. This material is in the shape of the filter bag 5 bent. At the junction 14 a fold is formed at which the filter bag 5 preferably closed by roll welding. To close on the upstream side is a fold 12 educated. The filter bag 5 is then along the fold 12 also preferably closed by roll welding. To the filter bag 5 is open in the filter bag 5 the spacer plate 8th inserted. To the individual filter bags 5 to the particle filter 1 to connect, the filter bags 5 along the top edge 24 form fit, preferably by welding, connected.

The inventive arrangement of the filter bags 5 to avoid tensions at the junction of the filter bags 5 with the outer retaining ring 2 is particularly suitable for all metallic filters in which the filter surfaces are connected to a flange or to a housing.

1

particulate Filter

2

outer retaining ring

3

internal retaining ring

4

drilling

5

filter bag

6

just Side wall

7

stretch direction

8th

shim

9

angle

10

Movement of the inner retaining ring 3 in tangential direction

11

curved Side wall

12

fold

13

Verbindnug the filter bags on the outflow side

14

junction

15

cavity

16

support ring

17

flow direction

18

outflow

19

casing

20

housing cover

21

Flange of the housing 19

22

Flange of the housing cover 20

23

Outside of the filter bag 5

24

top edge

Claims (12)

Particulate filter for cleaning exhaust gases of self-igniting internal combustion engines, filter bags ( 5 ) comprising at one end face in a form-locking manner with an outer retaining ring ( 2 ) and an inner retaining ring ( 3 ), characterized in that the filter bags ( 5 ) at an angle ( 9 ) to the radial position ( 8th ) are arranged twisted such that a longitudinal expansion ( 7 ) of the filter bags ( 5 ) in the radial direction to a movement ( 10 ) of the inner retaining ring ( 3 ) leads in the tangential direction. Particulate filter according to claim 1, characterized in that the angle ( 9 ) is at least 10 °. Particulate filter according to one of claims 1 or 2, characterized in that a twisted in a clockwise direction to the radial position arrangement of the filter bags ( 5 ) to a movement ( 10 ) of the inner retaining ring ( 3 ) in a counterclockwise direction and an anti-clockwise direction to the radial direction twisted arrangement of the filter straps ( 5 ) to a movement ( 10 ) of the inner retaining ring ( 3 ) in a clockwise direction. Particulate filter according to one of claims 1 to 3, characterized in that the filter bags ( 5 ) are made of sintered metal. Particulate filter according to one of claims 1 to 4, characterized in that the filter bags ( 5 ) with the outer retaining ring ( 2 ) are welded. Particulate filter according to one of claims 1 to 5, characterized in that the particulate filter ( 1 ) with the outer retaining ring ( 2 ) in a housing ( 19 . 20 ) is attached. Particulate filter according to claim 6, characterized in that the particulate filter ( 1 ) with the housing ( 19 . 20 ) is screwed. Particulate filter according to one of claims 1 to 7, characterized in that the filter bags ( 5 ) straight side walls ( 6 ) to have. Particulate filter according to one of claims 1 to 7, characterized in that the filter bags ( 5 ) curved side walls ( 11 ) to have. Particulate filter according to one of claims 1 to 9, characterized in that the filter bags ( 5 ) are closed on the inflow side and on the side facing towards the middle. Particulate filter according to one of claims 1 to 10, characterized in that in the filter bags ( 5 ) a spacer plate ( 8th ) is inserted. Particulate filter according to claim 11, characterized in that the spacer plate ( 8th ) corrugated sheet-shaped.