WO2006053750A1 - Device for purifying exhaust gases of an internal combustion engine that contain soot - Google Patents

Abstract

The invention relates to a device for purifying soot-containing engine exhaust gases (MG) of an internal combustion engine, particularly of a diesel engine, comprising a filter device (5, 10, 12, 17, 18), which is connected on the entrance side to an engine exhaust supply line (22) coming from the engine. The filter device (5, 10, 12, 17, 18) has a number of filter sections (1), and each filter section (1) comprises: at least one channel-shaped high-pressure inflowing section (2) that is connected to the engine exhaust supply line (22); a filter section (W), which is made of a porous material and which can be flowed through, and; at least one channel-shaped low-pressure outflowing section (3), which runs adjacent to the high-pressure inflowing section (2) and which leads into an exhaust evacuating line (23) provided on the exit side of the filter device (5, 10, 12, 17, 18), the high-pressure inflowing sections (2) and low-pressure outflowing sections (3) being parallel to one another. Inside the filter device (5, 10, 12, 17, 18) adjacent to the high-pressure inflowing section (2), at least one burner exhaust passage (4, 6), which is connected to a burner exhaust supply line (15), is provided for heating the high-pressure inflowing sections (2) and the filter sections (W).

Description

Device for cleaning soot-containing exhaust gases of an internal combustion engine

The invention relates to a device for cleaning soot-containing exhaust gases of an internal combustion engine, in particular a diesel engine.

Such a device is known from DE WO 00/50156. In this case, a filter device comprises a monolithic filter element made of porous SiC. The filter element is cylindrical and has a plurality of axially verlau¬ fender channels. First channels are connected at a first end of the filter element to an engine exhaust gas supply line coming from the engine and are closed at an opposite second end of the filter element. Second channels are closed at the first end of the filter element and verbun¬ the gegenüber¬ lying second end with a Abgasabführleitung the. The first channels are thus separated from the second channels by the surrounding porous walls. During operation of a diesel engine, the hot engine exhaust gases under high pressure flow from the engine exhaust gas supply line into the first channels and from there through their walls into the second channels. The soot contained in the engine exhaust gases is retained in the wall. The cleaned engine exhaust gases are discharged from the second channels via the Abgasabführleitung. Over time, the porous walls become clogged by the soot retained therein. During operation of the diesel engine, there then occurs an increase in the pressure in the engine exhaust gas discharge line and, as a result, a drop in power. To counteract this, when a particular limit value of the pressure in the engine exhaust gas feed line is exceeded, the combustion parameters are changed such that the temperature of the engine exhaust gas increases to such an extent and as a result the soot retained in the filter device is burned becomes. After the regeneration of the filter device effected in this way, the combustion parameters are adjusted again in such a way that an optimum engine output is achieved.

The known method requires a complex control device with which the temperature of the engine exhaust gases can be controlled as a function of the pressure in the engine exhaust gas supply line by appropriate control of the control times, the valves, an injection device, the ignition timing and the like. The provision of such a control device is expensive. Apart from that, the temperature increase of the engine exhaust gases required for the regeneration of the filter device can only be achieved if the diesel engine is operated with a high power. But that is not the case with all vehicles. In particular, in commercial vehicles, such as buses, refuse disposal vehicles and the like, which are used only in stationary traffic, the temperature increase of the engine exhaust gases required for the regeneration of the filter device is not achieved. In such vehicles, two filter devices are provided. If the filter element of a

Filter device is clogged, is switched to the other Filter¬ device. For regeneration clogged filter elements are removed and the soot collected in it burned out in an external furnace. It is obvious that this process is cumbersome, expensive and expensive.

From DE 198 10 738 Cl a filter device is known in which a burner is provided for regenerating a filter element. To burn off the soot, the filter element is heated at its exhaust gas discharge side facing Nieder¬ pressure side with hot burner exhaust gases. In practice, the known filter device has not proven itself. A complete combustion of the particular on the engine exhaust gas supply line facing high pressure side and provided in between the high pressure and the low pressure side Filtrationsabschnitt deposited carbon black can not be achieved er¬.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, a device as effective as possible for cleaning soot-containing exhaust gases of an internal combustion engine should be specified, which can be regenerated independently of the operating state of the internal combustion engine.

This object is solved by the features of claim 1. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 14.

According to the invention it is provided that within the filter device adjacent to the Hochdruckanstrδmabschnitt at least one, with a Brennerabgaszuführleitung verbunde¬ ner burner exhaust passage for heating the Hochdruckanström- and filter sections is provided. By providing a burner exhaust gas passage adjacent to the high-pressure inlet section, effective and complete combustion of the soot retained in the filter device can be achieved. Because of the provision of the burner exhaust gas passage, the combustion of the soot and thus the regeneration of the filter device can take place independently of the operating state of the internal combustion engine. The proposed device is particularly universal. It is particularly suitable for use in internal combustion engines, which are not operated for a long time or only for a short time at full power.

According to an advantageous embodiment of the invention, the burner exhaust gas passage also extends adjacent to the Niederdruck¬ outflow sections. This also allows heating of a high pressure flow section surrounded by low pressure exhaust sections. The Hochdruckanstrδmabschnitt is in heated in this case by means of heat conduction via the Niederdruckab- strömabschnitte.

The term "adjacent" is understood to mean an arrangement of the burner exhaust gas passage, which makes it possible to transfer heat sufficient for combustion of the soot to the high pressure inflow section and the associated filter section. To perform this function, the burner exhaust passage does not need to run immediately adjacent to the high pressure inflow section. It can be provided in between a gap or the like.

According to a further embodiment of the invention, the burner exhaust gas passage extends parallel and / or perpendicular to the high-pressure inflow section and / or to the low-pressure outflow sections. Conveniently, a plurality of burner exhaust passages are provided, which are arranged with a plurality of Hochdruckanströmabschnitten and Niederdruckabströmabschnitten for the most effective transmission of heat in the manner of a heat exchanger. The arrangement may correspond to that of a cross-flow heat exchanger, countercurrent heat exchanger or a mixed form of the aforementioned heat exchangers.

Advantageously, the burner exhaust gas passage is separated from the high-pressure inflow section by a first wall surrounding the high-pressure flow section. Thus, the burner exhaust gas passage and the burner connected therewith are substantially separated from the pressure prevailing in the high-pressure inflow section. This allows a particularly fast and effective discharge of the exhaust gases generated by the burner through the burner exhaust passage. The heat required for the regeneration of the filter device can be transmitted particularly quickly and efficiently. To decouple the burner exhaust gas passages from the pressure prevailing in the high-pressure inflow section, it is of course also possible that the Burner exhaust gas passage is limited by a surrounding wall.

According to a further embodiment of the invention, it is provided that the first wall of the high-pressure inflow section, the filter section and a second wall surrounding the low-pressure outflow section are made of the porous material. This allows a particularly simple and kostengün¬-term production of the filter device. For example, it can be inexpensively produced in large quantities by extrusion. Even if the first wall is produced only from a porous material, sufficient decoupling of the burner exhaust gas passage from the pressure prevailing in the high-pressure inlet section can thus be achieved.

According to a further embodiment, the filter section is at least partially formed by the first and / or second wall. For this purpose, in a particularly simple geometric configuration, the channel-shaped high-pressure inflow section may be surrounded by at least one, preferably several, channel-shaped low-pressure downflow sections arranged parallel thereto. Conveniently, in this case, the filter section extends over the entire length of the Hochdruckanström- or Niederdruckab- Strömabschnitts. It can be made available as a large filter surface Ver¬ addition.

The porous material is expediently made of porous silicon carbide. A surface of the material can be produced with catalytically active metals, for example Ru, Rh, Pt, Pd, Ir, Ni, Cu, V, W, Y, Ze, Ti, Zi or combinations or oxides thereof. The pores at least of the filter section expediently have an average pore size in the range from 100 to 200 μm. The first and / or the second Wall may have a different porosity with a mitt¬ ler pore size in the range of 40 to 80 microns.

Instead of silicon carbide, the porous material can of course also be made of other ceramic materials, for example cordierite, aluminum oxide, mullite, silicon oxide, zirconium oxide, titanium oxide, spinel or mixtures thereof.

According to a further embodiment of the invention, the filter device and the burner exhaust gas passage are surrounded by a common housing. In this case, flow guiding means for guiding the burner exhaust gases may be provided in the housing. It may be sheets, which one to the direction of z. B. in the form of straight long elongated channels formed Hochdrucküberströmabschnitte vertical flow of the burner exhaust gases.

The filter device may comprise one or more monolithically formed filter elements. Such monolithic filter elements can be produced, for example, by extrusion processes. For this purpose, the Hochdruckanstrδm- and Niederdruckabströmabschnitte may be designed as parallel channels, which are closed in a subsequent process to the extrusion process step to a part on one side and the other part on the other side. If the filter device comprises a plurality of filter elements, they can be arranged in a parallel arrangement in the housing. The remaining space between the filter elements in this case forms the burner exhaust passage. In this case, the filter elements can be flushed around to regenerate hot burner exhaust gases.

According to a further embodiment of the invention, a device for measuring the engine exhaust gas supply line is provided. visual pressure and a control device for switching on and off a connected to the Brennerabgaszuführleitung burner provided. The control device may comprise a microprocessor which switches the burner on and off according to a predetermined algorithm or program. The proposed device thus forms an independent system which, independently of the respective operating state of the combustion engine, acts to regenerate the filter device. Advantageously, the proposed device does not require any change in the combustion parameters during operation of the internal combustion engine. The internal combustion engine can be operated during the regeneration of the filter device without loss of performance.

According to a further embodiment, the Brennerabgas¬ passage opens into the Abgasabführleitung. Thus, it is advantageously not necessary to provide a separate exhaust gas discharge line for discharging the hot burner exhaust gases conducted through the burner exhaust gas passages. For this purpose, the exhaust-removal line already provided for discharging the engine exhaust gases can be used.

Embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

1 is a schematic sectional view through a Fil¬ terabschnitt a first filter device,

2 shows a perspective view of a second filter device,

3 shows a schematic sectional view according to the section line AA 'in FIG. 2, FIG. 4 shows a schematic sectional view according to the section line BB ¹ in FIG. 2, FIG.

5 shows a schematic cross-sectional view through a third filter device,

6 is a schematic cross-sectional view according to the section line AA ¹ in Fig. 5,

7 is a detail view of FIG. 6,

8 is a schematic sectional view through a fourth filter device,

9 is a schematic cross-sectional view according to the section line A-A 'in Fig. 8,

10 is a detail view of FIG. 9,

Fig. 11 is a schematic sectional view through a fifth

Filter device and

Fig. 12 is a schematic sectional view through a sixth

Filter device,

13 is a plan view of a device for Abgasrei¬ nigung and

14 shows a schematic cross-sectional view according to the section line A-A 'in FIG. 13.

1 shows a schematic sectional view through a monolithic filter element of a first filter device. The filter element is formed from a plurality of filter sections 1. Each of the filter sections 1 um- a high-pressure inlet channel 2 adjoins. Next to the high-pressure inlet channel 2, a low-pressure outlet channel 3 and / or a burner exhaust gas passage 4 can be provided. The Hochdruckanströmkanäle 2, the Niederdruckabströmkanäle 3 and the burner exhaust passage 4 are surrounded by walls W, which are made of a porous SiC ceramic.

The Hochdruckanströmkanäle 2 here parallel to the Niederdruckabströmkanälen 3 and the burner exhaust passage 4. The Hochdruckanströmkanäle 2 are connected to a (not shown here) Motorabgaszuführleitung. An entrance of the burner exhaust gas passage 4 is connected to a burner exhaust gas supply line (not shown here). An outlet of the burner exhaust gas passage 4 and openings of the low-pressure exhaust ducts 3 are connected to an exhaust discharge line (not shown).

In the filter element which operates according to the so-called "cross-flow principle", an engine exhaust gas MG containing soot is supplied to the high-pressure flow channels 2 under high pressure. The engine exhaust MG is pressed according to the arrows Pl through the walls W either in the Niederdruckabströmkanäle 3 or in the burner exhaust passage 4. In this case, the soot contained in the engine exhaust gas MG is retained in the walls W and possibly also in the high-pressure flow channels 2. Engine exhaust gas MGR purified in this way is discharged via the exhaust gas discharge line connected to the low-pressure discharge ducts 3 and the outlet of the burner exhaust gas passage 4.

If a pressure in the region of the high-pressure flow channels 2 or the engine exhaust gas supply line exceeds a certain limit value, hot burner exhaust gas BG is conducted through the burner exhaust gas passages 4. The soot-retaining walls W and the high pressure inflow sections 2 are heated to a temperature at which the soot burns. This will be the Regenerated filter element and is available for removing again soot from engine exhaust MG available.

FIG. 2 shows a perspective view of a second filter device 5. At a first end E1, engine exhaust gas MG laden with soot is supplied to the high-pressure inlet passages 2. At a second end E2 cleaned engine exhaust MGR leave the Niederdruckabströmkanäle 3. The Hochdruckanströmkanäle 2 are at the first end El open and at the second end E2 closed sen. The Niederdruckabströmkanäle 3 are closed at the first end El and open at the second end E2. As can be seen in particular with reference to FIGS. 3 and 4, slits 6 running parallel to the direction of the high-pressure inlet 2 and low-pressure outlet channels 3 are provided on upper and lower sides u extending transversely to the first El and the second end E2. The slots 6 extend from the first inlet openings 7 provided on the upper side o and second inlet openings 8 provided on the lower side u into the interior of the filter element 1. They open at the second end E2 into outlet openings 9 provided there.

Through the inlet openings 7, 8 hot burner exhaust gas BG is supplied. Cooled burner exhaust gas BGK is discharged through the outlet opening 9. The slots 6 are separated from the high pressure inflow passages 2 by the walls W surrounding them, so that a burner (not shown here) is substantially decoupled from the pressure prevailing in the high pressure inflow passages 2.

5 to 7 show a third filter device 10. The third filter device 10 comprises a plurality of, preferably rectangularly formed, first filter elements 11. The first filter elements 11 are arranged one above the other such that slots 6 extending parallel thereto are arranged form. In the embodiments shown, the slots 6 may generally have a width in the range of 1 to 6 mm, preferably 2 to 3 mm. The Hochdruckanströmkanäle 2 and the Niederdruckabströmkanäle 3 expediently in Ren ren a height and a width of 1 to 3 mm. The thickness of the surrounding walls W can be 0.5 to 2.0 mm.

In the third filter device 10, the hot burner exhaust gas BG flows through the slots 6 in a direction transverse to

Direction of Hochdruckanstrόm- 2 and Niederdruckabströmkanäle 3.

FIGS. 8 to 10 show a fourth filter device 12. In this case, a multiplicity of second filter elements 14, which are formed cylindrically here, are provided in a housing 13. For attachment of the second filter elements 14 (not shown here) spacers may be received in the housing 13. The second filter elements 14 are arranged at a distance a of 1 to 6 mm. An inlet 15 is connected to a burner exhaust gas supply line (not shown here) and an outlet 16 is connected to an exhaust gas discharge line (not shown here). Within the housing 13, there are flow guide plates 16a provided transversely to the second filter elements 14, which, in accordance with the arrows P2, force a flow of the hot burner exhaust gases BG which extends substantially perpendicular to the second filter elements 14. As can be seen in particular from FIG. 8, the hot burner exhaust gases BG are supplied in the fourth filter device 12 in the region of the second end E 2 and are led off in the region of the first end E 1, ie. H. they are guided according to the countercurrent principle.

As can be seen from FIG. 10, the low-pressure discharge channels 3 are open in the region of the second end E 2, where, however, conditions the Hochdruckanströmkanäle 2 are closed in the region of the second end E2.

11 and 12 show a fifth 17 and a sixth filter device 18. In this case, in the housing 13 again rectangular or cuboid-shaped first Filterelemen¬ te 11 are arranged in different ways, so that therebetween in the fifth filter device 17 transverse to the direction the high-pressure inlet channels 2 and the low-pressure outlet flow channels 3 provided slots 6 extend. In the case of the sixth filter device 18, slits 6 extending at right angles to one another are provided which extend transversely to the direction of the high-pressure flow channels 2 and the low-pressure flow channels 3.

FIGS. 13 and 14 show a device for exhaust gas purification. A monolithically formed third filter element 19 is accommodated in the housing 13. The third filter element 19 has diagonal slots 6. Two burner exhaust gas supply lines 15 lead away from a burner, indicated schematically by the reference numeral 20, which is provided with a blower 21 for supplying air to be heated. An engine exhaust gas feed line is designated by the reference numeral 22. It is connected only to the high pressure contact channels 2 of the third filter element 19 (not shown here).

The function of the device is as follows:

Hot exhaust gas loaded with soot and supplied with soot through the engine exhaust gas supply line 22 enters the high-pressure flow channels 2 of the third filter element 19 under high pressure. The hot engine exhaust gases MG are forced through the walls W into the low-pressure outflow channels 3. In this case, the soot contained in the hot engine exhaust gases MG in the walls W zurück- held. The cleaned engine exhaust gas MGR leaves the device via the exhaust gas discharge line 23.

To regenerate the third filter element 19, hot burner exhaust BG is generated by cooperation of the burner 20 and the blower 21, which penetrates into the slots 6 both at the top o and at the bottom u and the third filter element 19 at a temperature at which the soot deposited in the walls W burns. The exhaust gases formed in this way are also discharged through the Abgasabführlei¬ device 23.

LIST OF REFERENCE NUMBERS

1 filter section

2 high-pressure inlet channel

3 Niederdruckabströmkanal

4 burner exhaust passage

5 second filter device

6 slot

7 first entrance opening

8 second inlet

9 outlet opening

10 third filter device

11 first filter element

12 fourth filter device

13 housing

14 second filter element

15 inlet

16 outlet

16a flow baffle

17 fifth filter device

18 sixth filter device

19 third filter element

20 burners

21 blowers

22 engine exhaust gas supply line

23 Abgasabführ1eitung

a distance BG hot burner exhaust gas

BGK cooled burner exhaust gas

El first end

E2 second end

MG soot containing engine exhaust MGR purified engine exhaust o top u bottom w wall

Claims

claims 1. Device for cleaning soot-containing engine exhaust gases (MG) of an internal combustion engine, in particular a diesel engine, with a filter device (5, 10, 12, 17, 18) connected on the input side to a motor exhaust line (22) coming from the engine, wherein the filter device (5, 10, 12, 13, 17, 18) comprises a multiplicity of filter sections (1 ), each filter section (1) having at least one channel-shaped high-pressure inlet section (2) connected to the engine exhaust gas supply line (22), a filter section (W) made of a porous material and at least one adjacent to the high-pressure inlet section (2 ) has the channel-shaped Niederdruckabströmabschnitt (3), which in an output side of the filter means (5, 10, 12, 17, 18) provided Abgasabführleitung (23) opens, wherein the Hochdruckanstrδm- (2) and the Niederdruckabströmab¬ sections (3) are arranged parallel to each other, characterized in that within the filter device (5, 10, 12, 17, 18) adjacent to the high-pressure inflow section (2) at least one burner exhaust passage (4, 6) connected to a burner exhaust gas supply line (15) for heating the high-pressure impingement (2) and filter sections (W) are provided. 2. Device according to claim 1, wherein the Brennerabgasdurch¬ transition (4, 6) adjacent to the Niederdruckabströmabschnitten (3) runs. 3. Device according to one of the preceding claims, wherein the burner exhaust gas passage (4, 6) parallel and / or perpendicular to the Hochdruckanströmabschnitt (2) and / or to the Nieder¬ druckabströmabschnitten (3). 4. Device according to one of the preceding claims, wherein the burner exhaust gas passage (4, 6) from the Hochdruckanströmab¬ section (2) by a the Hochdruckanstömabschnitt (2) um¬ giving first wall is separated. 5. Device according to one of the preceding claims, wherein the first wall of the Hochdruckanströmabschnitts (2), the Fil¬ terabschnitt (W) and a second the Niederdruckabströmab¬ section (3) surrounding wall made of the porous material are manufactured. 6. Device according to one of the preceding claims, wherein the filter section (W) is at least partially formed by the first and / or second wall. 7. Device according to one of the preceding claims, wherein the porous material is porous silicon carbide. 8. Device according to one of the preceding claims, wherein the filter means (5, 10, 12, 17, 18) and the Brennerab¬ gas passage (4, 6) of a common housing (13) are umge¬ ben. 9. Device according to one of the preceding claims, wherein in the housing (13) flow-guiding means (16 a) for guiding Burner exhaust gases (BG) are provided. 10. Device according to one of the preceding claims, wherein the filter device comprises one or more monolithically formed filter element / s (11, 14, 19). 11. Device according to one of the preceding claims, wherein the burner exhaust passage (4, 6), the filter elements (11, 14, 19) surrounds. 12. Device according to one of the preceding claims, wherein there is provided a device for measuring the pressure prevailing in the engine exhaust gas supply line (22) and a control device for switching on and off a burner (20) connected to the burner exhaust gas supply line (15) are. 13. Device according to one of the preceding claims, wherein the control device comprises a microprocessor. 14. Device according to one of the preceding claims, wherein the burner exhaust passage (4, 6) in the Abgasabführlei¬ device (23) opens.