DE4213822A1 - Internal combustion engine exhaust gas filter - Google Patents

Abstract

Filter comprises housing (1) in which the gas passes with low flow restriction from inlet(s) to outlet(s) (3) via (i) an expansion space (4) with a cross-section which is a multiple of the inlet flow cross-section; (ii) a disc (5) having an outer perforated region (5b) for gas passage and a central region (5a) which seals the expansion space (4) gas-tightly w.r.t. the rest of the housing; and (iii) filter insert(s) (8) between two perforated cylindrical casings (6,7) which are coaxial with one another and with the housing axis (1a). Pref. disc (5) is omitted and (i) the expansion space (4) contains filter unit(s) for filtering the exhaust gas which flows into a second expansion space contg. the filter insert (8) and the casings (6,7); or (ii) the or each filter insert (8) comprises heat resistant alumina, silica, aluminosilicate, ceramic, cellulose and/or glass fibres of mixts. with other heat resistant fibres.

Description

This application is an additional application to that in German European Patent Application No. 91106 907.8, filed with European Patent Office on April 28, 1991. In the European patent application the Federal Republic of Germany is designated as a contracting state.

The invention relates to an improved device for exhaust gas purification, in particular for more efficient cleaning of exhaust gases from internal combustion engines. The invention also relates to a method for cleaning exhaust gases. In this procedure Particular attention, if not exclusive, to cleaning of exhaust gases from internal combustion engines, in particular from internal combustion engines for operation in motor vehicles.

In the European patent application 91 106 907.8 a device for Filtering exhaust gases from internal combustion engines in the area of the exhaust system between the exit of the exhaust gases from the combustion chamber and the outflow of the Exhaust gases in the area around the exhaust tailpipe. The establishment according to of the European patent application comprises a device with one in the Exhaust gas flow can be installed at any point in the exhaust system, one or more Inlet opening (s) and one or more outflow opening (s) Housing and with devices arranged in the housing for low throttling Guiding the exhaust gas flow from the inflow opening (s)

• - An expansion space, the cross section of the flow cross section of the Inflow opening (s) exceeds several times,
• - one in the outer area with a large number of holes to flow through the exhaust gas provided, in the central area opposite the expansion space the remaining area of the housing with a gastight sealing ring plate,  
• - One between a first perforated cylinder jacket, the axis is coaxial to the housing axis, and a second perforated cylinder jacket, whose axis is coaxial with that of the first cylinder jacket and one larger circumference than the first cylinder jacket, arranged Filter insert, and
• - then directly to the outlet opening (s) of the housing in Direction towards the exhaust tailpipe of the Ab gas system.

One of the essential objects of the invention, that of the European patent application 91 106 907.8 was the basis, was the guarantee of an effective Filtration of combustion gases with as little throttling as possible Flow rate of the combustion gases. This was especially in the Regarding the use of the filter device in the filtration of Ver Combustion gases from car engines are important in order to achieve that with the effective Filtration associated with the smallest possible reduction in the engine output can be.

The present invention has for its object, with effective filtration of combustion gases to further reduce the throttling of the Exhaust gas flow rate to come. This became important viewed to a filtration of combustion gases even when large Ensure quantities of exhaust gases, such as those not only in power plants, but also occur in large-volume internal combustion engines, including motor vehicle engines. To take into account that not all motor vehicle engines already with the equipped with the latest technical knowledge are. Some of the existing facilities are for certain engine types (Otto leaded fuel engines; Diesel engines, two-stroke engines) not yet either satisfactory.

In the prior art, it had also frequently been criticized that throughput high amounts of exhaust gas through a with a fibrous or particulate filter material loaded filter there was a risk that in particular smaller particles of the The filter material is blown out of the filter by a strong flow of exhaust gas were. In addition to the problem that these particles may be harmful to health were harmful, the filter pack was gradually loosened, which the Filtration effect decreased unacceptably in the long run.

Another object of the present invention was therefore a Provide device for filtering exhaust gases in which a discharge is smaller Particles of the filter material are not produced by the exhaust gas flow and therefore also ensures a long-term satisfactory filtration effect of the filter material can be.

Another disadvantage of the prior art was that the Filter pack especially when the engine emitting combustion gases was not always operated in the optimal capacity, with fixed Exhaust gas components, such as soot, added. As a result, not only that After filtration effect, but there was also an increasing throttling of the Determine exhaust gas flow. This undesirably reduced engine performance increasingly. As a result, the filter had to be cleaned or replaced more often be rare.

Another object of the invention was to provide a filter material to provide, the components of which can contribute to one increasing clogging of the filter pack, especially with a fixed exhaust gas inventory share, prevent.  

Surprisingly, it has now been found that the above tasks with the improved filter device according to the invention and the modified method for exhaust gas purification can be solved by filtration.

The invention relates to a device for filtering exhaust gases from Ver internal combustion engines according to claim 1. Preferred embodiments such a device result from the back-related to claim 1 Subclaims and the following description.

The invention also relates to a device for filtering exhaust gases Internal combustion engines according to claim 12. Preferred embodiment Form such a device result from the claim 12 related subclaims and the following description.

The invention also relates to a method for purifying exhaust gases Internal combustion engines by filtration according to claims 20 and 21. Preferred embodiments of the method are those of claims 20 and 21 related subclaims and the following description remove.

Exhaust gases from internal combustion engines are used in the present application, as in European Patent Application No. 91 106 907.8, exhaust gases from Internal combustion engines understood how they are operated in motor vehicles. As Examples are gasoline engines (two- or four-stroke engines) with any Fuels or fuel mixtures including hybrid engines and diesel engines ren (two- or four-stroke engines) called. Basically, the invention is suitable appropriate filter device but also for the filtration of other exhaust gases, even if them below with particular reference to the filtration of exhaust gases from Motor vehicle internal combustion engines is described. The versatile use The facility's availability is one of its advantages over the prior art.  

The invention will now be described with reference to the drawings explained. Show it:

Figure 1 as an embodiment of the invention, a preferred device for filtering exhaust gases in longitudinal section.

FIG. 2 shows a cross section through the device according to FIG. 1 at the point labeled "II";

FIG. 3 shows a cross section through the device according to FIG. 1 at the point labeled "III";

FIG. 4 shows a cross section through the device according to FIG. 1 at the point labeled "IV";

FIG. 5 shows a cross section through the device according to FIG. 1 at the point labeled "V";

FIG. 6 shows the device according to FIG. 1, in which the gas flows were drawn in during operation;

Fig. 7 as another embodiment of the invention, a more preferred means for filtering exhaust gases in longitudinal section; and

Fig. 8 as a further embodiment of the invention, a third preferred device for filtering exhaust gases in longitudinal section.

The inventive device for filtering exhaust gases from combustion engines can be anywhere in the exhaust system of a motor vehicle between the point at which the exhaust gases exit the combustion chamber and  the point at which the exhaust gases at the exhaust tailpipe flow into the environment, to be built in. It is in it - as is the establishment according to the above European patent application mentioned - comparable facilities of the state superior to technology. According to the invention, it is preferred that the filter device is installed in the so-called muffler. However, there are other areas of the Exhaust system suitable for installation.

The filter device according to the invention comprises a housing 1 which has one or more inflow opening (s) 2 and one or more outflow opening (s) 3 . These are connected to the person skilled in the known means with the exhaust gases feeding parts 2 a and the exhaust gases dissipating parts 3a of the exhaust system configured connectable and means for operation of the filter according to the invention with this detachable manner.

In the housing 1 of the filter device according to the invention there are or are arranged devices for guiding the exhaust gas flow from the inflow opening (s) 2 with little throttling

• an expansion space 4 , the cross section of which exceeds the flow cross section of the inflow opening (s) 2 by a multiple,
• - at least one perforated between a first cylinder casing 6, whose axis is coaxial with the axis of the housing 1 a, and a second perforating th cylinder jacket 7, whose axis is coaxial of the first Zylin dermantels 6 and having a larger circumference than the first cylinder jacket 6 arranged filter insert 8 , and
• - Then directly to the outflow opening (s) 3 of the housing 1 in the direction of the exhaust tailpipe of the exhaust system located downstream.

According to one embodiment of the invention, the filter device in the area of the expansion space 4 has one or more filter unit (s) 17 for filtering the exhaust gases, which flow out of the filter unit (s) 17 into a second expansion space 15 , from where they flow reach at least one filter insert 8 arranged between the first perforated cylinder jacket 6 and the second perforated cylinder jacket 7 .

As such, the external shape of the housing 1 is not critical. It can preferably be cylindrical. However, a cuboid shape is also possible. Likewise, several of the geometric shapes mentioned can be coupled side by side to form an arrangement of a plurality of filter devices connected to one another in parallel or in series. This is particularly recommended for internal combustion engines with a large amount of exhaust gas.

In a preferred embodiment, the housing of the filter device according to the invention can consist, for example, of an outer cylinder jacket with a removable cover 9 with the inflow opening (s) 2 and a removable bottom 10 with the outflow opening (s) 3 . Lid 9 and bottom 10 are attached to the outer cylinder jacket with releasable fixing devices 9 a for the lid and releasable fixing devices 10 a for the bottom. This arrangement considerably facilitates the replacement or control of the filter unit (s) 17 and the filter insert or the filter inserts 8 .

The expansion space 4 can be sealed in a preferred embodiment of the filter device according to the invention by means of an annular plate 5 from the remaining part of the housing 1 to the extent that a gas flow is only possible via the filter units 17 in the remaining area of the housing. The ring plate 5 thus primarily shields the regions located in front of the filter units 17 in a gas-tight manner from the rest of the housing ( FIG. 2). At the level of the area behind the filter units 17 , a second ring plate 5 b shields the expansion space 4 from the rest of the housing in a gas-tight manner ( FIG. 3). The arrangement of the two ring plates 5 , 5 b is such that an exhaust gas flow from the expansion space 4 into the second expansion space 15 can only take place via the filter unit (s) 17 .

In a further preferred embodiment of the filter device according to the invention, devices 5 a for directing the exhaust gas flow are arranged in the expansion space 4 in front of the filter unit (s) 17 . These have the advantage that they ensure a uniform distribution of the exhaust gas flow for the inflow of the filter unit (s) 17 . In a particularly preferred embodiment, the devices 5 a for guiding the exhaust gas flow from an annular plate 5 'are placed on the optionally conical flow divider 5 a, the cone ring tip pointing counter to the flow direction of the exhaust gas flow ( Fig. 2).

In a further embodiment of the device according to the invention, it is possible for the ring plate 5 to completely cover the expansion space 4 against the area in which the filter units 17 are flowed against. In this case, the ring plate 5 can have openings or holes in the outer region lying between the housing 1 and the inner part of the ring plate 5 , through which the exhaust gases flow in order to flow against the filter units 17 . Through these breakthroughs or holes, the exhaust gases can flow from the expansion space 4 into the area of the inflow to the filter unit (s) 17 . The shape of the openings or holes in the ring plate 5 is not critical; however, they should be large enough so as not to give rise to a substantial restriction of the exhaust gas flow.

The filter unit (s) 17 can be made of any material that allows filtration of the exhaust gases for the purpose of separating solid exhaust gas components from the exhaust gas stream and afterburning incompletely oxidized exhaust gas components. The filter unit (s) 17 preferably consist of a fine-pored material with a heat resistance that allows contact with the relatively hot combustion gases. The material is therefore to be selected according to criteria known to the person skilled in the art in such a way that the required heat resistance is given as a function of the temperature of the respective combustion gases.

When operating the filter device according to the invention in the exhaust system of internal combustion engines of motor vehicles, the filter units 17 preferably consist of a fired inorganic oxide material, particularly from the group of ceramic materials, particularly preferably from the group of fired ceramic materials. Oxidic materials which contain SiO ₂ , Al ₂ O ₃ and / or ZrO ₂ or consist of one or more of these compounds have proven particularly useful in practice. In the case of fibrous materials, the fibers preferably have a length between 2 and 50 mm and a diameter in the range from 5 to 40 μm.

The oxidic materials can advantageously be in the form of plates, disks, punched or cut moldings of suitable thickness and optionally with Use a round cross-section in which the fibers are parallel to the largest upper body surface are aligned, i.e. perpendicular to one of the small plates or disks Side surfaces. This results in an orientation of the fibers parallel to Flow direction of the exhaust gases during operation of the device according to the invention.

In a particularly preferred embodiment, the fibers of the material of the filter unit (s) 17 are in the form of one or more stacks (s) of annular plates, the outer diameter of which corresponds to the inner diameter of the filter unit (s) 17 holding the gas-permeable cylinder and the inner diameter of which Outer diameter of the gas-permeable inner cylinder holding the filter unit (s) corresponds exactly to fit. There are no gaps between the individual annular plates of the stack (s), which contain the fibers parallel to the flow direction of the gases, which would allow unfiltered exhaust gases to pass through. This is of course undesirable, since it would significantly reduce the efficiency of the filtration, since exhaust gases could pass through the filter unit (s) 17 that did not flow through the filter unit and therefore still contained the components to be removed in whole or in part.

According to a preferred embodiment of the invention, the oxidic materials of the filter unit (s) 17 are acted upon by a catalytically active material in the oxidation of hydrocarbons, carbon and / or partially oxidized carbon compounds. According to the surprising results of the experiments which led to the present invention, copper and / or silver and / or cobalt and / or chromium and / or manganese and / or their compounds, in addition to other metals which give less good results, are best suited for this purpose.

In a particularly preferred embodiment of the invention, more or less readily soluble salts of the metals mentioned are provided in water or aqueous solvents. Aqueous solvents are mixtures of water with protic organic solvents, preferably alcohols with 1 to 4 carbon atoms, especially with ethanol, or also with amines and / or ethers. In the salts, the solubility in the solvents or solvent mixtures mentioned can be improved, for example by complex formation. According to the invention, copper salts complexed with ammonia or with organic amines are particularly suitable. For example, the copper tetrammin cation [Cu (NH ₃ ) ₄ ] ⁺ is advantageously used as the cation of the salts used according to the invention. However, the use of copper salts of the formula is also advantageous
(Cu (NR ¹ R ² R ³ ) ₄ ⁺,
wherein R ¹ , R ² and R ^{3 may be the} same or different and are independently hydrogen, alkyl groups with 1 to 6 carbon atoms or hydroxyalkylene groups with 1 to 4 carbon atoms in the alkylene radical or at least two of the radicals R ¹ , R ² and R ³ are linked to form a saturated or unsaturated heterocyclic ring system. It is also possible that two nitrogen atoms each carry two substituents R ¹ , R ² and R ³ and via an alkylene group bridging both nitrogen atoms
- (CHR ⁴ ) _n -
are connected, wherein R ^{4 represents} hydrogen, an alkyl group having 1 or 2 carbon atoms or a hydroxy group and n is an integer in the range between 1 and 3. As complexing agents for the copper ion, different amine ligands can also be present in a complex.

Examples of suitable complexes are copper tetrammine salts, copper tetrakis (monoethylamine) salts, copper tetrakis (diethylarlin) salts, copper tetrakis (mono ethanolamine) salts, copper bis (ethylenediamine) salts, copper bis (tetramethyl ethylenediamine) salts and corresponding salts in which mixed amine ligands are present. The compounds used with advantage are the anionic ones Salt partners also complex ions, for example borate ions, phosphate ions, etc. Copper tetrammine borate is particularly preferred.

The salts mentioned can be obtained in any way known to those skilled in the art ceramic materials are applied. For example, from plates fibrous materials cut or punched circular rings that the corresponding devices of the filter are adjusted in their diameter so that the rings later fill the filter containers completely in stacks. The Rings cut or punched so that the grain runs perpendicular to the narrow Outside of the rings and towards the inside of the ring, d. H. parallel to the later Flow direction of the exhaust gases. The rings are then with a impregnated with an aqueous or aqueous-alcoholic solution of the salts mentioned, for example with an aqueous-alcoholic (50/50 v / v) solution of copper tetram  minborate. Thereafter, the impregnated rings may become minor dried at elevated temperatures and then in the facility for Filtering of exhaust gases installed. Similarly, it is possible to use the rings after the Cut or punch out first in the second for filtration Install cylinder jacket and impregnation and drying afterwards to provide or any other procedure as long as one complete impregnation of the filter media with the catalytically active material can be adequately ensured. Variations of together The setting of the solvents and the concentrations of the salts are carried out by experts shear assessment possible in a wide range without the area of Invention is hereby left.

The filter materials according to the invention, in particular the filter materials with copper and / or manganese and / or silver salts impregnated on the surface, achieve rates of oxidation of unburned or incompletely burned hydrocarbons or of soot which meet the current standards of all industrialized countries. In particular, the amount of pollutants, in particular soot and CO, but also NO _x , which occurs in large quantities when cold started, is surprisingly noticeably reduced. Soot that is initially deposited is later burned to CO ₂ without residue when the exhaust gas temperatures rise. This prevents clogging of the filters. CO is completely burned to CO ₂ and does not leak into the environment.

In a further preferred embodiment of the filter according to the invention means 17 is arranged a second expansion chamber 15 (s) following the filter unit, the gases after leaving the / filter unit (s) 17 flow to the probe. Flow dividers 16 are preferably arranged in the second expansion space 15 in order to bring about a distribution of the exhaust gas flow over the inflow to the filter insert 8 . An arrangement of the flow dividers 16 transverse to the flow direction of the gases is advantageous. With this arrangement it is achieved that a uniform distribution of the exhaust gas flow for the further flow takes place. As such, the shape of the flow dividers is not critical as long as they ensure an even distribution of the exhaust gas flow. In the particularly preferred embodiment shown in FIG. 1, the flow divider consists of a ring with a central opening arranged at right angles to the housing wall in the exhaust gas flow direction after the filter inserts 17 . The exhaust gases advantageously flow through the central opening and are evenly distributed by the inflow pressure onto the filter insert (s) 8 arranged downstream of the exhaust gas. Also in the case of this flow divider, a plate is provided in a preferred embodiment of the invention, which has suitably large bores or holes in the central area through which the exhaust gases can flow into the area of the filter inserts 8 . As such, the shape of the bores or holes is not critical as long as it does not result in a substantial restriction of the exhaust gas flow.

In a further preferred embodiment of the filter device according to the invention, a plurality of filter inserts 8 , preferably for example two filter inserts, are arranged in front of the outflow opening (s) 3 . In the embodiment shown in FIG. 1, however, for the sake of simplicity, only one filter insert 8 is arranged in front of the outflow opening 3 .

The filter inserts extend between a first perforated cylinder jacket 6 , the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket 7 , the axis of which is coaxial with the housing axis and coaxial with the axis of the first cylinder jacket 6 . The second cylinder jacket 7 has a larger circumference than the first cylinder jacket 6 , so that between the two cylinder jackets 6 , 7 results in a cross-sectionally annular space in which the filter insert 8 is arranged. Its thickness is not critical in itself; however, it must be so thick that sufficient filtering of the exhaust gases is achieved without substantial throttling of the exhaust gases. Practically, the thickness is in the range between 10 and 25 mm, particularly preferably 15 to 20 mm, but is not restricted to this range. However, the best filtration results are achieved in this area.

Instead of the two perforated cylinder jackets 6 , 7 , woven fabrics or nets made of wire can also be used in order to give the filter insert material 8 the necessary mechanical hold.

The filter insert or the filter inserts 8 can consist of a loosely packed non-woven fabric in which the cotton-like disordered fibers generally have different lengths and have to be stable against elevated temperatures in order not to cake or melt together to form a mass, which then throttles of the exhaust gas flow and thus a reduction in engine performance. According to a preferred embodiment of the invention, however, each filter insert 8 consists of heat-resistant aluminum oxide fibers, silicon oxide fibers, aluminum oxide-silicon oxide fibers, ceramic fibers, glass fibers, cellulose fibers and mixtures thereof. However, mixtures of the fibers mentioned with other suitable heat-resistant fibers or fibers which are covered with a heat-resistant layer made of one of the above-mentioned materials can also be used. In a particularly preferred embodiment, the fiber diameters are 3 to 50 μm, most preferably 3 to 10 μm. Thinner fibers are not used due to their health-endangering properties.

For the fibers of the filter inserts 8 , the materials already used above in connection with the filter units 17 are used in the form of one or more stacks (s) of annular plates, the outer diameter of the plates being the inner diameter of the second cylinder jacket 7 and the inner diameter of the plates the outer diameter of the first cylinder jacket 6 corresponds exactly. Under no circumstances should there be gaps between the annular plates of the stack (s) which would allow the passage of non-filtered gases.

Rather, the ring plate stacks are packed tightly and without gaps.

In a preferred embodiment of the device according to the invention, the oxidic materials of the filter insert (s) 8 are acted upon by a material which is catalytically active in the oxidation of hydrocarbons, carbon and / or partially oxidized carbon compounds. According to the surprising results of the experiments which led to the present invention, copper and / or silver and / or cobalt and / or chromium and / or manganese and / or their compounds, in addition to other metals which give less good results, are best suited for this purpose.

In a particularly preferred embodiment of the invention, more or less readily soluble salts of the metals mentioned are provided in water or aqueous solvents. Aqueous solvents are mixtures of water with protic organic solvents, preferably alcohols with 1 to 4 carbon atoms, especially with ethanol, or also with amines and / or ethers. In the salts, the solubility in the solvents or solvent mixtures mentioned can be improved, for example by complex formation. According to the invention, copper salts complexed with ammonia or with organic amines are particularly suitable. For example, the copper tetrammin cation [Cu (NH ₃ ) ₄ ] ⁺ is advantageously used as the cation of the salts used according to the invention. However, the use of copper salts of the formula is also advantageous
(Cu (NR ¹ R ² R ³ ) ₄ ) ⁺,
wherein R ¹ , R ² and R ^{3 may be the} same or different and are independently hydrogen, alkyl groups with 1 to 6 carbon atoms or hydroxyalkylene groups with 1 to 4 carbon atoms in the alkylene radical or at least two of the radicals R ¹ , R ² and R ³ are linked to form a saturated or unsaturated heterocyclic ring system. It is also possible that two nitrogen atoms each carry two substituents R ¹ , R ² and R ³ and via an alkylene group bridging both nitrogen atoms
- (CHR ⁴ ) _a -
are connected, wherein R ^{4 represents} hydrogen, an alkyl group having 1 or 2 carbon atoms or a hydroxy group and n is an integer in the range between 1 and 3. As complexing agents for the copper ion, different amine ligands can also be present in a complex.

Examples of suitable complexes are copper tetrammine salts, copper tetrakis (monoethylamine) salts, copper tetrakis (diethyiamine) salts, copper tetrakis (mono ethanolamine) salts, copper bis (ethylenediamine) salts, copper bis (tetramethyl ethylenediamine) salts and corresponding salts in which mixed amine ligands are present. The compounds used with advantage are the anionic ones Salt partners also complex ions, for example borate ions, phosphate ions, etc. Copper tetrammine borate is particularly preferred.

The salts mentioned can be obtained in any way known to those skilled in the art ceramic materials are applied. For example, from plates fibrous materials cut or punched circular rings that the corresponding devices of the filter are adjusted in their diameter so that the rings later fill the filter containers completely in stacks. The Rings cut or punched so that the grain runs perpendicular to the narrow Outside of the rings and towards the inside of the ring, d. H. parallel to the later Flow direction of the exhaust gases. The rings are then with a impregnated with an aqueous or aqueous-alcoholic solution of the salts mentioned, for example with an aqueous-alcoholic (50/50 v / v) solution of copper tetram minborate. Thereafter, the impregnated rings may become minor dried at elevated temperatures and then in the facility for  Filtering of exhaust gases installed. Similarly, it is possible to use the rings after the Cut or punch out first in the second for filtration Install cylinder jacket and impregnation and drying afterwards to provide or any other procedure as long as one complete impregnation of the filter media with the catalytically active material can be adequately ensured. Variations of together The setting of the solvents and the concentrations of the salts are carried out by experts shear assessment possible in a wide range without the area of Invention is hereby left.

The substances with which the material of the filter insert / the filter inserts 8 is applied can, however, also have other functions, for example from sorbing functions. Suitable absorbents are, for example, activated carbons, which are applied to the materials of the filter insert in a more or less thin layer / bed.

In a further preferred embodiment of the filter device according to the invention, the nets or fabrics made of wire, which instead of the cylinder sheaths 6 , 7 give the filter insert 8 mechanical support, can be coated with a catalyst material which catalyzes the reactions described above.

Alternatively, it corresponds to a further preferred embodiment of the Invention, such substances elsewhere in the exhaust stream, both within the filter device according to the invention as well as before or after it in the exhaust gas trom, to arrange or to apply. In a particularly preferred embodiment form of the invention is a conventional controlled catalyst with a Combined filter device according to the invention, resulting in a special environmentally friendly exhaust gas purification through catalysis and combined filtration the exhaust gases. This embodiment of the invention leads to in practice surprising results in that even the strictest norms of exhaust gas values  be fulfilled.

A further preferred embodiment of the filter device according to the invention can be seen in the fact that a device 8 a for protecting the filter material against inflowing solid parts of the exhaust gas is arranged in front of each filter insert 8 in the exhaust gas flow direction. This has the advantage that such filters cannot reach the filter materials themselves and consequently cannot become blocked. The devices 8 a for protecting the filter material can consist of any material suitable for this purpose.

According to further preferred embodiments of the device according to the invention, as alternatively shown in FIGS. 7 and 8, the invention relates to a device for filtering exhaust gases from internal combustion engines in the area of the exhaust system between the exhaust gases exiting the combustion chamber and outflowing into the environment at the exhaust -The tailpipe, which has a mountable in the exhaust gas flow at any point in the exhaust system, one or more inlet opening (s) 2 and one or more outlet opening (s) 3 housing 1 and arranged in the housing 1 devices for low-throttle control of the exhaust gas flow from the / the inflow opening (s) 2 through

• an expansion space 4 , the cross section of which exceeds the flow cross section of the inflow opening (s) 2 by a multiple,
• at least one filter insert 8 arranged between a first perforated cylinder jacket 6 , the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket 7 , the axis of which is coaxial with that of the first cylinder jacket 6 and which has a larger circumference than the first cylinder jacket 6 , and
• thereafter includes directly to the outflow opening (s) 3 of the housing 1 in the direction of the exhaust tailpipe of the exhaust system located downstream,

wherein the material of the filter insert (s) 8 comprises heat-resistant aluminum oxide fibers, silicon oxide fibers, aluminum oxide-silicon oxide fibers, ceramic fibers, cellulose fibers, glass fibers and their mixtures or mixtures of the said fibers with other heat-resistant fibers.

The preferred form of the fiber materials and the exact possible arrangement of the fibers in the filtration materials, as well as the application of certain catalysts, preferably copper catalysts, to the fiber materials has already been mentioned above in connection with the other preferred embodiments of the invention, in particular in connection with the filter inserts 8 and the filter units 17 explained. Repetition is therefore omitted here, the materials and shapes used precisely in the particularly preferred embodiments according to FIGS. 7 and 8 which were also mentioned above as preferred.

At the outlet of the filter devices according to the invention, the filtered exhaust gases pass through one or more outflow opening (s) 3 into the exhaust gas exhaust system or into an end pipe which leads the exhaust gases into the open. The outflow opening (s) 3 can have any diameter which is suitable for the purpose to the person skilled in the art. According to the invention, they preferably have a round or oval diameter, without the invention being restricted to this.

In the process according to the invention for cleaning exhaust gases, in particular from internal combustion engines, by filtration in a housing 1 comprising one or more inflow opening (s) 2 and one or more outflow opening (s) 3 , which can be fitted into the exhaust gas flow at any point in the exhaust system, with devices for The exhaust gases thus become low-throttling guidance of the exhaust gas flow

• guided from the inflow opening (s) 2 through an expansion space 4 , the cross section of which exceeds the flow cross section of the inflow opening (s) 2 by a multiple,
• - Arranged between a first perforated cylinder jacket 6 , the axis of which is coaxial with the housing axis 1 a, and a second perforated cylinder jacket 7 , the axis of which is coaxial with that of the first cylinder jacket 6 , and which has a larger circumference than the first cylinder jacket 6 Filter insert 8 out, and
• - Directly to the outflow opening (s) 3 of the housing 1 in the direction of the exhaust pipe downstream of the exhaust system, the exhaust gases in the area of the expansion space 4 through one or more filter unit (s) 17 Filtration of the exhaust gases are conducted and after exiting the filter unit (s) 17 through a second expansion space 15 to the filter insert (s) 8 before they pass through the outflow opening (s) 3 into the exhaust system or into the open.

Compared to the embodiment of European Patent Application No. 91 106 907.8, there are procedural differences due to the passage of the filter unit (s) 17 . Furthermore, according to the invention, an improvement in the filtration performance is achieved by enlarging the filter area of the filter unit (s) following the second expansion space. This leads to the fact that the emergence of fibers or filter material particles from the filter inserts 8 is significantly reduced, if not prevented.

In a further preferred embodiment of the method according to the invention, the exhaust gases from the inflow opening (s) ( 2 )

• - guided through an expansion space ( 4 ), the cross section of which exceeds the flow cross section of the inflow opening (s) ( 2 ) by a multiple,
• - By at least one between a first perforated cylinder jacket ( 6 ), the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket ( 7 ), the axis of which is coaxial with that of the first cylinder jacket ( 6 ) and which has a larger circumference than the first cylinder jacket ( 6 ), arranged filter insert ( 8 ), and
• - then led directly to the outflow opening (s) ( 3 ) of the housing ( 1 ) in the direction of the exhaust tailpipe of the exhaust system located downstream,

wherein the exhaust gases are passed through one or more filter inserts ( 8 , 17 ) in which the fibers of the material are in the form of one or more stacks (s) of annular plates, the outer diameter of which corresponds to the inner diameter of the second cylinder jacket ( 7 ) and the inner diameter of which The outer diameter of the first cylinder jacket ( 6 ) corresponds to a precise fit, there being no gaps between the annular plates of the stack (s) which allow unfiltered gases to pass through.

The individual fibers in the annular plates or in the material of the filter inserts 8 are advantageously arranged essentially in the direction which corresponds to the direction of flow of the exhaust gases through the filter inserts.

In a further advantageous and therefore preferred embodiment of the method the exhaust gases after leaving the / are the filter unit (s) to a plurality of exhaust gas downstream or passed 17 to the / filter unit (s) 17 arranged current divider sixteenth A process control in which the exhaust gases are directed around flow dividers 16 which are arranged transversely to the flow direction of the exhaust gases is particularly preferred. This results, for example, from the embodiment shown in FIG. 1.

In a further preferred procedure, the exhaust gases are fed to a plurality of filter inserts 8 after exiting the filter unit (s) 17 and, if appropriate, after passing through the flow dividers 16 . This increases the filter area available for the filtration of the exhaust gases and thus achieves more efficient filtration with less throttling of the exhaust gas flow and thus largely avoiding a reduction in engine output. A process control in which the exhaust gases are fed to at least two filter inserts 8 arranged around an outflow opening 3 is particularly preferred. Efficient filtering of the exhaust gases is achieved in a space-saving manner. The increase in the area of the filter units largely prevents throttling of the exhaust gas flow.

The filter device according to the invention can be manufactured in a manner known per se Wise done, it being considered advantageous that mass production can be implemented without great technical effort.

Another significant advantage is the fact that both the unit with the filter inserts 8 and the filter units 17 can be exchanged much better during service and overhaul work than was possible with previously known filter inserts. In addition to the improved cleaning of the exhaust gases, the filter device according to the invention also saves on service time in that it is no longer necessary to disassemble and disassemble the entire device. In addition, a blockage of the filter materials and thus an increasing throttling of the exhaust gas flows through the catalytic degradation, for example through combustion, of the substances that could possibly cause a blockage are avoided. The filter device of the invention is therefore also surprisingly superior to prior art devices.

Claims (29)

1.Device for filtering exhaust gases from internal combustion engines in the area of the exhaust system between the exit of the exhaust gases from the combustion chamber and outflow into the environment at the exhaust tailpipe with one or more inflow openings (s) which can be mounted in the exhaust gas flow at any point in the exhaust system ( 2 ) and one or more outflow opening (s) ( 3 ) comprising housing ( 1 ) and devices arranged in the housing ( 1 ) for guiding the exhaust gas flow from the inflow opening (s) ( 2 ) with little restriction

• an expansion space ( 4 ), the cross section of which exceeds the flow cross section of the inflow opening (s) ( 2 ) by a multiple,
• - at least one between a first perforated cylinder jacket ( 6 ), the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket ( 7 ), the axis of which is coaxial with that of the first cylinder jacket ( 6 ) and which has a larger circumference than the first cylinder jacket ( 6 ), arranged filter insert ( 8 ), and
• - then directly to the outflow opening (s) ( 3 ) of the housing ( 1 ) in the direction of the exhaust tailpipe of the exhaust system located downstream,

wherein the device in the area of the expansion space ( 4 ) has one or more filter unit (s) ( 17 ) for filtering the exhaust gases, which flow out of the filter unit (s) ( 17 ) into a second expansion space ( 15 ), from from where they reach the at least one filter insert ( 8 ) arranged between the first perforated cylinder jacket ( 6 ) and the second perforated cylinder jacket ( 7 ). 2. Device according to claim 1, which in the expansion space ( 4 ) in front of the filter unit (s) ( 17 ) arranged devices ( 5 a) for guiding the exhaust gas flow. 3. Device according to claim 2, wherein the devices ( 5 a) for guiding the exhaust gas flow from an annular plate ( 5 ), on which optionally kegelringför shaped flow dividers ( 5 a) are placed, the cone ring tip pointing counter to the flow direction of the exhaust gas flow. 4. Device according to one or more of claims 1 to 3, wherein the filter unit (s) ( 17 ) consist of a fine-pored material with a heat resistance that allows contact with combustion gases. 5. Device according to claim 4, wherein the filter unit (s) ( 17 ) a fired inorganic oxide material, preferably a fired ceramic material, particularly preferably a SiO ₂ , Al ₂ O ₃ and / or ZrO ₂ comprising and / or one or more of the above Material containing oxides, which may be loaded with one or more substances that contribute to further detoxification of the exhaust gases. 6. Device according to one or more of claims 1 to 5, wherein in the second expansion space ( 15 ) flow dividers ( 16 ) are arranged to cause a distribution of the exhaust gas flow to the inflows to the filter insert ( 8 ). 7. Device according to one or more of claims 1 to 6, wherein a plurality of filter inserts ( 8 ) in front of the or the outflow opening (s) ( 3 ) are arranged. 8. Device according to claim 7, wherein two filter inserts ( 8 ) are arranged in front of each outflow opening ( 3 ). 9. Device according to one or more of claims 1 to 8, wherein a device ( 8 a) for protecting the filter material from solid exhaust gas components is arranged in the exhaust gas flow direction before each filter insert ( 8 ). 10. Device according to one or more of claims 1 to 9, wherein the outflow opening (s) ( 3 ) has a round or oval diameter. 11. The device according to one or more of claims 1 to 10, wherein the material of the filter insert / the filter inserts ( 8 ) heat-resistant aluminum oxide fibers, silicon oxide fibers, aluminum oxide-silicon oxide fibers, ceramic fibers, cellulose fibers, glass fibers and their mixtures or mixtures of said fibers with other heat-resistant fibers. 12.Device for filtering exhaust gases from internal combustion engines in the area of the exhaust system between the exit of the exhaust gases from the combustion chamber and outflow into the environment at the exhaust tailpipe with one or more inflow openings (s) which can be mounted in the exhaust gas flow at any point in the exhaust system ( 2 ) and one or more outflow opening (s) ( 3 ) comprising housing ( 1 ) and devices arranged in the housing ( 1 ) for guiding the exhaust gas flow from the inflow opening (s) ( 2 ) with little restriction

• an expansion space ( 4 ), the cross section of which exceeds the flow cross section of the inflow opening (s) ( 2 ) by a multiple,
• - at least one between a first perforated cylinder jacket ( 6 ), the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket ( 7 ), the axis of which is coaxial with that of the first cylinder jacket ( 6 ) and which has a larger circumference than the first cylinder jacket ( 6 ), arranged filter insert ( 8 ), and
• - then directly to the outflow opening (s) ( 3 ) of the housing ( 1 ) in the direction of the exhaust tailpipe of the exhaust system located downstream,

the material of the filter insert (s) ( 8 ) comprising heat-resistant aluminum oxide fibers, silicon oxide fibers, aluminum oxide-silicon oxide fibers, ceramic fibers, cellulose fibers, glass fibers and mixtures thereof or mixtures of the said fibers with other heat-resistant fibers. 13. The device according to claim 12, wherein the fibers of the material of the filter insert (s) ( 8 , 17 ) is in the form of one or more stacks (s) of annular plates, the outer diameter of the inner diameter of the second cylinder jacket ( 7 ) and the inner diameter corresponds to the outer diameter of the first cylinder jacket ( 6 ) with a precise fit, there being no gaps between the annular plates of the stack (s) which allow unfiltered gases to pass through. 14. Devices according to claim 12 or 13, wherein the individual fibers in the annular plates or in the material of the filter cartridges ( 8 , 17 ) are arranged substantially in the flow direction of the exhaust gases through the filter cartridge / the filter cartridges. 15. The device according to one or more of claims 1 to 14, wherein the material of the filter insert (s) ( 8 , 17 ) is acted upon by one or more substances which contribute to a further detoxification of the exhaust gases. 16. The device according to claim 15, wherein substances for further detoxification of the exhaust gases Are catalysts or absorbents or composites of these materials.   17. The device of claim 16, wherein the catalysts are oxidation catalysts are, preferably catalytically active noble metals and / or ceramic materials. 18. The device of claim 16, wherein the absorbents comprise activated carbon. 19. Device according to one or more of claims 1 to 18, wherein the catalysts comprise salts of copper and / or silver and / or cobalt and / or chromium and / or manganese, preferably salts of copper, particularly preferably borates of copper of the general formula of the cation
[Cu (NR ¹ R ² R ³ ) ₄ ] ₊ ,
wherein R ¹ , R ² and R ^{3 may be the} same or different and are independently hydrogen, alkyl groups having 1 to 6 carbon atoms or hydroxyl alkylene groups having 1 to 4 carbon atoms in the alkylene radical or at least two of the radicals R ¹ , R ² and R ³ are linked to form a saturated or unsaturated heterocyclic ring system. 20. Method for cleaning exhaust gases from internal combustion engines by filtration in a housing ( 1 ) comprising one or more inflow opening (s) ( 2 ) and one or more outflow opening (s) ( 3 ) which can be mounted in the exhaust gas flow at any point in the exhaust system. with devices for low throttling of the exhaust gas flow, wherein the exhaust gases from the inflow opening (s) ( 2 )

• - are led through an expansion space ( 4 ), the cross section of which exceeds the flow cross section of the inflow opening (s) ( 2 ) by a multiple,
• - By at least one between a first perforated cylinder jacket ( 6 ), the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket ( 7 ), the axis of which is coaxial with that of the first cylinder jacket ( 6 ) and which has a larger circumference than the first cylinder jacket ( 6 ), arranged filter insert ( 8 ) are guided, and
• - are then led directly to the outflow opening (s) ( 3 ) of the housing ( 1 ) in the direction of the exhaust tailpipe of the exhaust system located downstream,

the exhaust gases in the area of the expansion space ( 4 ) being passed through one or more filter unit (s) ( 17 ) for filtering the exhaust gases and after exiting the filter unit (s) ( 17 ) through a second expansion space ( 15 ) are fed to the filter insert (s) ( 8 ) before they reach the exhaust system or the outside through the outlet opening (s) ( 3 ). 21. Method for cleaning exhaust gases from internal combustion engines by filtration in a housing ( 1 ) which can be fitted into the exhaust gas flow at any point in the exhaust system and has one or more inflow openings ( 2 ) and one or more outflow openings ( 3 ). with devices for low throttling of the exhaust gas flow, wherein the exhaust gases from the inflow opening (s) ( 2 )

• - are led through an expansion space ( 4 ), the cross section of which exceeds the flow cross section of the inflow opening (s) ( 2 ) by a multiple,
• - By at least one between a first perforated cylinder jacket ( 6 ), the axis of which is coaxial with the housing axis, and a second perforated cylinder jacket ( 7 ), the axis of which is coaxial with that of the first cylinder jacket ( 6 ) and which has a larger circumference than the first cylinder jacket ( 6 ), arranged filter insert ( 8 ) are guided, and
• - are then led directly to the outflow opening (s) ( 3 ) of the housing ( 1 ) in the direction of the exhaust tailpipe of the exhaust system located downstream,

wherein the exhaust gases are passed through one or more filter inserts ( 8 , 17 ) in which the fibers of the material are in the form of one or more stacks (s) of annular plates, the outer diameter of which corresponds to the inner diameter of the second cylinder jacket ( 7 ) and the inner diameter of which The outer diameter of the first cylinder jacket ( 6 ) corresponds to a precise fit, there being no gaps between the annular plates of the stack (s) which allow unfiltered gases to pass through. 22. The method according to claim 20, wherein the exhaust gases after passing out of the filter unit (s) ( 17 ) are passed around one or more flow dividers ( 16 ) arranged transversely to the flow direction of the exhaust gases. 23. The method according to one or more of claims 20 to 22, wherein the exhaust gases are optionally fed to a plurality of filter inserts ( 8 ) after exiting from the filter unit (s) ( 17 ) and optionally after passing through the flow dividers ( 16 ). 24. The method according to claim 23, wherein the exhaust gases are supplied to at least two filter inserts ( 8 ) arranged around an outflow opening ( 3 ). 25. The method according to one or more of claims 20 to 24, wherein the individual fibers in the annular plates or in the material of the filter inserts ( 8 ) are arranged substantially in the flow direction of the exhaust gases through the filter insert / the filter inserts.