DE102009029259A1 - Exhaust gas aftertreatment device has filter arrangement, which has two housings separated from each other, where particle filter element is arranged in housing in each case so that two soot filters are formed - Google Patents

Abstract

The exhaust gas aftertreatment device (1) has a filter arrangement, which has two housings (2) separated from each other. A particle filter element (3,4) is arranged in the housing in each case so that two soot filters (5,6) are formed. A filter element-free through line is arranged within the soot filter, where the through line is closed in a circumferential direction. The latter soot filter is downstream to the former soot filter. An independent claim is also included for a method for controlling an exhaust gas stream by an exhaust gas aftertreatment device.

Description

The invention relates to an exhaust gas aftertreatment device with a filter arrangement, which has at least two separate housings, in each of which at least one particle filter element is arranged, so that two soot filters are formed, which are arranged in an exhaust line.

Such exhaust aftertreatment devices or filter arrangements are z. B. arranged in exhaust lines of internal combustion engines, and exemplified as a diesel particulate filter, when the internal combustion engine is a diesel engine.

The DE 40 04 424 A1 discloses a device for cleaning the exhaust gases of diesel engines, in which the exhaust pipe of the engine divides into two by means of a switching alternately lockable branch lines, one of which leads via a soot filter, behind which this serves with the other serving as a bypass line branch line to an end reunited. The leading via the soot filter branch line is opened with the help of operable depending on the engine load switching device from a predetermined part load and full load of the engine. In order to ensure a virtually complete cleaning of the exhaust gases, an oxidation catalyst is installed behind the switching device in the bypass line or in the final line. If the oxidation catalyst is installed in the end line, this is traversed by the entire exhaust gas.

The DE 10 2004 049 511 A1 On the other hand, it deals with a semi-active, heat-exchanging silencer, which is followed by a catalytic converter. In order to avoid heat loss of the exhaust gases after a start of the internal combustion engine by a compact component, and to bring about a heat loss when the engine is at operating temperature, two different flow paths are provided in the muffler, one of which is thermally insulated, whereas the other flow path is designed so that the exhaust gases are cooled.

The DE 10 2005 019 466 A1 again, it deals with a diesel particulate filter for an exhaust system of an internal combustion engine having at least one housing and at least one filter body. The filter device comprises at least two fluidically arranged in series filter body. The filter bodies are spaced from each other in a common housing. Chambers are provided between the filter bodies, in each of which externally connected lines open.

Exhaust gas aftertreatment devices in the configuration as a particle filter or as a soot filter require periodic regeneration by burning the collected soot particles. In order to perform the regeneration, it requires an increase in the exhaust gas temperature to an amount over z. B. 550 ° C to initiate the burning of the collected soot particles. In lean internal combustion engines, such as diesel engines, these temperature levels are only reached during normal operation of the internal combustion engine under full load when the soot filter is located close to the engine. Near-engine means that the particulate filter is located so close to an exhaust gas outlet of the internal combustion engine that heat losses of the exhaust gases are minimized on your flow path to the particulate filter during high-temperature regeneration, but also to a desired passive regeneration, which in a temperature window of z. B.: 200 ° to 350 ° C during the actual function of the soot filter, so can take place the catching or filtering out of particles from the exhaust gases. Since the soot filter is located very close to the exhaust outlet, and here little space is available, design parameters, so the size and capacity of the soot filter are limited to the available space. Further, the design of the exhaust pipe (Koni, bends) lead to a suboptimal flow distribution. This immediately causes a significant pressure drop across the soot filter for high flow rates, which has a negative effect on fuel consumption of the engine, especially in so-called highway rides.

It is therefore an object of the invention to improve an exhaust aftertreatment device or its filter arrangement of the type mentioned above with simple means such that the negative effects on fuel consumption are avoided despite a soot filter arranged close to the engine.

According to the invention, the object is achieved with an exhaust gas aftertreatment device having a filter arrangement with the features of claim 1, wherein within a first soot filter a shut-off by means of a control, circumferentially closed, filter element-free passage line is arranged, which passes completely through only the particulate filter element of the first soot filter, and wherein at least a second soot filter is connected downstream of the first soot filter.

Advantageously, at least two soot filter elements are arranged in series in an exhaust pipe or in an exhaust line, so that a low pressure drop in spite of high flow rate and thus an improved fuel consumption in connection can be achieved with a caused by the or the soot filter, increased backpressure.

It is expedient if the first soot filter is arranged close to the engine, upstream of the second soot filter.

Favorable in the context of the invention is when the control is designed as a control flap, which is switchable between a blocking the passage line and the passage line opening position. Of course, it can be provided to carry out the control flap as a continuously closing element, so that the control flap can release the through-line in accordance with the engine load continuously between the two extreme positions in intermediate positions or open. Advantageously, the control is switchable so that a small amount of exhaust gas flow by blocking the passage line through the particulate filter element of the first soot filter, and then flows through the particulate filter element of the second soot filter due to the series connection. On the other hand, the control element is switchable so that flows from the amount of high exhaust gas flow by releasing the passage line therethrough and through the particulate filter element of the second soot filter.

Since the first soot filter is only flowed through when the exhaust gas flow is small, ie at a low to medium load of the internal combustion engine, it can be made smaller in its capacity and size. This is particularly advantageous in the very small available space in the near-motor position. A generated back pressure is limited mainly by the maximum soot load with low exhaust gas flow rate. This is the main filter mechanism at low to medium engine load, which, due to the near-engine position, has a direct beneficial effect on a high passive degree of regeneration during the capture or filtering out of soot particles from the exhaust stream and on a high thermal level with minimal thermal losses during regeneration ,

At medium to high engine loads (ie at high exhaust gas volume flow), the exhaust gas flow through the passage line is passed through the first soot filter connected in series second soot filter, which is arranged remote from the engine with respect to the first soot filter. The second soot filter can advantageously be arranged in a location in which a compromise between capacity, size and space is not required. Therefore, it is possible to arrange the second soot filter along the exhaust pipe at a suitable place under the underbody. The capacity and size of the second soot filter can therefore be designed to be larger in relation to the first soot filter, in order to be able to filter the high exhaust gas volume flow, while at the same time ensuring a low back pressure at high exhaust gas volume flow.

It is essential that a filter system is provided which has a first soot filter for low flow rates and the second soot filter for high flow rates to reduce the pressure drop across the filter system at high flow rates, at the same time the Regenerationseffektivität due to the smaller, close to the engine arranged soot filter (Filter system for low flow rates) is improved.

Further advantageous embodiments are disclosed in the subclaims and the following sequence description. Show it

1 a filter assembly in a schematic representation with open passage line, and

2 the filter assembly in a schematic representation with open passage line.

In the different figures, the same parts are always provided with the same reference numerals, so that these are usually described only once.

The 1 and 2 show an exhaust aftertreatment device 1 with a filter assembly, which at least two separate housing 2 in which in each case at least one particulate filter element 3 . 4 is arranged so that two soot filters 5 . 6 are formed in an exhaust line 7 are arranged.

The exhaust system 7 is shown only as a section, and leads exhaust gases from an exhaust outlet, not shown, of an internal combustion engine, which is exemplified as a diesel engine, first to the first soot filter 5 , from here via a connector 8th to the second soot filter 6 , From the second soot filter 6 the exhaust gases are in a tail 9 the exhaust line 7 guided, in which further components can be arranged. The exhaust gas volume flow is shown starting from the internal combustion engine, not shown, by means of the directional arrows. The connector 8th is shown in its course only by way of example and may also have other suitable, adapted to a mounting situation execution.

In or within the first soot filter 5 is one by means of a control 10 lockable, circumferentially closed, filter element-free passage line 9 is arranged, which only the particulate filter element 3 in the first soot filter 5 engages, and wherein the first soot filter 5 the second soot filter 6 is downstream. The two soot filters 5 and 6 in the exhaust system 7 are connected in series.

The housing 2 of the first soot filter 5 has a conically expanding input side 11 , a substantially cylindrical filter area 12 and a conically tapered exit side 13 on. The housing 2 of the second soot filter 6 is carried out analogously thereto, which is why the same reference numerals are used here.

The particle filter element 3 of the first soot filter 5 is in the filter area 12 arranged. The transit line 9 only reaches through the particle element 3 Completely. The passage line protrudes on the input side 9 with their inlet side 14 something in the conically executed input side 11 , With its outlet side 16 protrudes the passage line 9 something in the conical output side 13 , Of course, both the exhaust side 16 as well as the inlet side 14 the transit line 9 flush with the surface of the particulate filter element 3 complete, or further exemplified in the output side 13 or in the input side 11 protrude. It is essential that the transit line 9 only the particulate filter element 3 of the first soot filter 5 engages, and the inlet side 14 the transit line 9 not the entry side 11 be upheld. The effective filter area of the first soot filter 5 is the effective area of the passage line 9 or the control surface of the control 10 (if this in the closed position 17 or switched to an intermediate position) is reduced.

The control 10 is designed as a control flap, which between a the passage line 9 blocking or closing position 17 ( 1 ) or one the transit line 9 opening or releasing position 18 ( 2 ) is switchable. Of course, the control can 10 also be designed so that between the extreme positions 17 or 18 stepless positions can be adjusted so that the passage line 9 fully closed, partially closed / opened or completely closed, depending on the engine load. For example, the control may be coupled to a control unit (ECU) of the internal combustion engine.

An example is the control 10 in the inlet side 14 the transit line 9 arranged. It is conceivable the control 10 in the outlet side 16 the transit line 9 , or at a suitable location between the inlet side 14 and the outlet side 16 to arrange.

Again 1 can be seen by way of example, is the passage line 9 with its central axis X congruent, so congruent to the central axis X1 of the first soot filter 5 arranged. The transit line 9 is in the illustrated view designed as a cylindrical pipe, but of course other, suitable embodiments, if appropriate.

The first soot filter 5 is arranged close to the engine. Close to the engine in the sense of the invention means that the first soot filter 5 is arranged so close to an exhaust gas outlet of the internal combustion engine that heat losses of the exhaust gases are minimized on their flow path to the soot filter during high-temperature regeneration, but also to a desired passive regeneration, which in a temperature window of z. B.: 200 ° to 350 ° C during the actual function of the soot filter, so can take place the catching or filtering out of particles from the exhaust gases.

Based on the second soot filter 6 is the first soot filter 5 dimensioned a little smaller or designed, which is also due to the very small space capacities close to the internal combustion engine. However, the small dimensions of the first soot filter 5 certainly not a disadvantage, but not only based on the space requirements and also based on a lower pressure drop and thus on improved fuel economy advantageous. Because the first soot filter 5 or its particle filter element 3 can be reduced in size, since the particulate filter element 3 flows through the exhaust stream only at low to medium engine loads. This is done by means of the control 10 reached, which is the transit line 9 closes at low to medium engine loads, such as 1 exemplifies.

In this respect, the transit line 9 at a low amount of exhaust gas volume flow by means of the control element 10 closed. The exhaust gases flow through the particle filter element 3 , which filters out the particulates or soot mainly from the exhaust gases. This represents the main filter mechanism at low to medium engine load, due to the near-engine position of the first soot filter 5 directly beneficial to a high level of passive regeneration during the collection or filtering out of particles or soot particles from the exhaust stream and to a high thermal level with minimal thermal losses during regeneration. The cleaned exhaust gases leave the first soot filter and flow along the exhaust line 7 or its connector 8th in the second soot filter 6 one.

Is the transit line 9 by means of the control 10 at medium to high engine loads open ( 2 ), the exhaust gases flow mainly unpurified through the first soot filter 5 along the transit line 9 over the connector 8th in the second soot filter 6 or flow through the particle filter element 4 , which filters out the particles or soot from the exhaust gases. Is the control in the position 18 switched, so provides the second soot filter 6 Of course, a small part of the exhaust gases, which is not through the passage line 9 flows through the particulate filter element 3 of the first soot filter 5 flow, which is not detrimental.

As already indicated, the second soot filter is 6 larger in capacity and dimensions than the first soot filter 5 executed. This is possible because the second soot filter 6 based on the first soot filter 5 is arranged remotely, so for example along the exhaust line 7 below the underbody of the motor vehicle (under floor). The second soot filter 6 can be advantageously arranged in a place where a compromise between capacity, size and space is not required. The capacity and size of the second soot filter 6 Can therefore be based on the first soot filter 5 be designed to be larger in order to filter the high exhaust gas flow rate, while a low backpressure at high exhaust gas flow rate can be ensured.

As stated above, the control can 10 variable in its position between the two extremes 17 and 18 be switched. For example, a desired distribution of the exhaust gas streams (preferably depending on engine load) may be achieved by the first soot filter 5 or its particle filter element 3 and the transit line 9 be controlled, so that a division of the degree of filtration by means of the first and / or second Rußfilters 5 respectively. 6 is reachable. Also, the first soot filter may be designed as a so-called "open filtration element", wherein a filtering out of particles from the exhaust gases no longer takes place when the absorption capacity of the first soot filter 5 is exhausted. That from the first soot filter 5 exiting exhaust gas and the entrained particles are then from the second soot filter 6 treated or filtered out by this.

At high exhaust gas flow rate, the required regeneration temperature (> 500 ° C) z. B. achieved by means of higher outlet temperatures of the exhaust gases from the engine (average to high engine load).

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 4004424 A1 [0003]
• DE 102004049511 A1 [0004]
• DE 102005019466 A1 [0005]

Claims (7)

Exhaust after-treatment device with a filter arrangement ( 1 ), which at least two separate housing ( 2 ), in which in each case at least one particle filter element ( 3 . 4 ), so that two soot filters ( 5 . 6 ) are formed, characterized in that within a first soot filter ( 5 ) one by means of a control ( 10 ) lockable, circumferentially closed, filter element-free passage line ( 9 ), which only the particle filter element ( 3 ) and that the first soot filter ( 5 ) at least the second soot filter ( 6 ) is connected downstream. Exhaust after-treatment device according to claim 1, characterized in that the soot filters ( 5 . 6 ) in series in an exhaust line ( 7 ) are arranged. Exhaust after-treatment device according to claim 1 or 2, characterized in that the first soot filter ( 5 ) close to the engine upstream of the second soot filter ( 6 ) is arranged. Exhaust after-treatment device according to one of the preceding claims, characterized in that the first soot filter ( 5 ) is made smaller in its capacity and / or in its dimension than the second soot filter ( 6 ), which relative to the first soot filter ( 5 ) is arranged remotely. Exhaust after-treatment device according to one of the preceding claims, characterized in that the control element ( 10 ) is switchable so that this the passage line ( 9 ) completely closes or completely opens. Exhaust after-treatment device according to one of the preceding claims, characterized in that the control element ( 10 ) is switchable so that the passage line ( 9 ) steplessly between a closed position ( 17 ) and an open position ( 18 ) is switchable. Method for controlling an exhaust gas flow through an exhaust gas aftertreatment device with a filter arrangement ( 1 ), in particular according to one of the preceding claims, wherein the filter arrangement ( 1 ) at least two separate housing ( 2 ), in which in each case at least one particle filter element ( 3 . 4 ), so that two soot filters ( 5 . 6 ) are formed, characterized in that an exhaust gas flow depending on engine loads by means of a control element ( 10 ), which in one, the particulate filter element ( 3 ) of the first soot filter ( 5 ) thoroughgoing transmission line ( 9 ) is controllable so that the exhaust gas flow through either the particulate filter element ( 3 ) of the first soot filter ( 5 ) and / or through the particulate filter element ( 4 ) of the second soot filter ( 6 ) flows.

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