Exhaust gas treatment system for an internal combustion engine

0001The present invention relates to an exhaust gas treatment arrangement with at least one exhaust gas treatment catalyst exhaust gases from an internal combustion engine with at least one exhaust gas discharge port.

0002For reducing pollutants in exhaust gases from internal combustion engines are catalytic converters in the exhaust system of the internal combustion engine arranged. The exhaust line comprises at least a group of a plurality of directly to the exhaust gas discharge ports designated coupled particular as exhaust manifolds Pipe pieces, which of the exhaust gas discharge ports record ejected gases. On this pipe pieces are pipe junctions coupled to the exhaust gases from the several gas discharge ports of a group of gas discharge ports to collect in a single tube, to which a silencer is connected, from which the exhaust gas is finally discharged to the environment. Before entering in the muffler passes through the exhaust gas to an exhaust gas catalyst, in which contained in the exhaust gas pollutants, such as For example, CO and NOx into less harmful Products are converted. is, for motor vehicles the exhaust catalyst usually on together with the silencer The vehicle floor of the motor vehicle disposed.

0003To the efficient treatment of the exhaust gas of the exhaust gas catalyst has have an increased operating temperature of for example about 600 ° C. During a cold start of the internal combustion engine is a certain Period of time required until the exhaust gas catalyst its intended finished warming up, during which time optimum treatment of the exhaust gases is not possible and issued correspondingly increased amounts of pollutants into the environment will. This period of time is at a floor of the vehicle arranged catalytic converter, among other reasons comparatively long as the catalytic converter with a relatively large distance of the internal combustion engine is arranged, and the exhaust gases due on entering the catalytic converter the heat exchange between the internal combustion engine and catalytic converter provided pipe connections compared to exit directly from the internal combustion engine are strongly cooled.

0004Therefore, exhaust gas catalysts have been developed which more closely at the internal combustion engine, for example in the exhaust manifold arranged and which are accordingly after a cold start quickly reach their intended operating temperature, which itself may even be higher than that of comparable Catalytic converters which are arranged in the region of the vehicle floor are.

0005Such close to the exhaust gas discharge port of the internal combustion engine arranged catalytic converter is known from US 6,062,020 known. This catalytic converter has a catalyst support body of frustoconical shape in which in a conically tapered exhaust pipe is inserted. Of the Catalyst support body is against the conically tapered Tube supported by a fiber mat. The fiber mat has a certain elasticity, which the sensitive Catalyst support body from the close to the internal combustion engine strong vibrations occurring protects.

0006This mounting concept for the catalyst carrier body is however felt to be disadvantageous, since proper to Holding the catalyst carrier body of a relatively precisely adjusted axial pressure in the conically must be pressed tapered tube section. Further includes this mounting concept using cylindrical Catalyst support bodies from which on a view a flow of the same advantageous would.

0007Accordingly, an object of the present invention, a propose exhaust treatment device, with which particular cylindrical catalyst support body close to the Internal combustion engine can be arranged.

0008In a first aspect, the invention is based on a Exhaust gas treatment device for an internal combustion engine with at least one exhaust gas discharge port, wherein a plurality of catalytic converters are provided, and wherein each exhaust gas catalyst a separate exhaust gas discharge port of the internal combustion engine assigned. The catalytic converter includes a Catalyst carrier body, which provides a surface, where the catalyst material is provided, which the chemical reaction for the conversion of the harmful promotes products of combustion into less harmful products. In particular, the catalyst carrier body in its interior a plurality of flow channels provided, the inner surface are provided with the catalyst material. The Flow channels are preferably channels along its length is substantially uniform cross-section to a flow through the catalytic converter with the lowest possible Flow losses to allow. Accordingly, the Catalyst support body has a substantially cylindrical shape on, the cylindrical shape is not necessarily the must have the form of a circular cylinder. Rather, cylindrical shapes provided with any base, such as hexogonaler or square base.

0009The catalyst carrier body is in a catalyst holding tube added that the indirect to the exhaust gas discharge port Internal combustion engine is coupled. Preferably, the catalyst holding tube but directly, ie without the introduction of additional separate tube sections coupled to the exhaust gas discharge port.

0010The invention is characterized in this case by the fact that the Catalyst holding tube in succession two pipe portions, wherein the catalyst support body, seen in The direction of flow of the exhaust gas, in a front first pipe section is accommodated, which has a larger inner diameter has as a first tube region in the flow direction the exhaust subsequent second tubular portion.

0011This interpretation is based on the consideration that from the Total cross-section of the catalyst carrier body, only a Part as a flow cross-section for the exhaust gas available stands. In view of a reduction of flow losses in the catalyst support body whose cross section is compared increased to the cross section of the second tube portion.

0012In particular, it is provided that the cross-section of the Exhaust gas catalyst carrier body is equal to or greater than the Inner diameter of the second tube portion.

0013With regard to a simple manufacture of the catalyst holding tube this is preferably made of a single piece of pipe integrally molded. This means that the first and the second pipe section is not provided by separate pieces of pipe are represented by connection techniques such as assembled welding or screwing are.

0014In a second aspect, the invention provides an internal combustion engine-close Assembly of catalytic converters before, wherein each catalytic multiple exhaust discharge ports the internal combustion engine is associated, however, with no a single catalytic converter exhaust all discharge ports assigned. Accordingly, several catalytic converters provided, of which each in a separate Catalyst holding tube is added. Accordingly, in Upstream of the catalytic converter a manifold provided to a catalyst holding tube of each multi- to couple gas discharge ports. Furthermore, in Downstream of the plurality of catalytic converters a Pipe-gathering provided to the plurality of catalyst-retaining tubes merge into a single continuing exhaust pipe.

0015Preferably, as a transition between the first and second pipe section inserted a third pipe section, whose internal diameter is smaller than that of the first tube portion and is greater than that of the second tube portion. This third tubular portion is preferably a radial shoulder ready to which the catalyst support body itself or with the interposition of a further support structure is axially supported so that it in against slippage fixed an axial direction to the second tube portion toward is.

0016In contrast to the example on the vehicle floor briefly arranged upstream of the silencer the exhaust gas catalyst is at issue in engine-close exhaust catalyst special mechanical and thermal stresses and particularly increased flow pulsations exposed. On Such engine-near the exhaust catalyst is preferably less than 1 m, in particular less than 0.5 m and in particular less than 0.25 m from the internal combustion Machine remotely located, wherein this length is not a geometric distance between the catalyst carrier body and the internal combustion engine refers, but to a length the pipe connection between the catalyst carrier body and exhaust gas discharge port the internal combustion engine.

0017Preferably, the catalyst carrier body is through the pipe flange pass incorporated into the catalyst holding tube, and although more preferably such that the catalyst carrier body taken with its entire length in the first pipe section is.

0018The catalyst support body can, for example, by a ceramic structure, a metallic structure or a be formed other structure but because of the Regard to a large catalyst surface as possible large number of flow channels mechanically fragile and is sensitive to deformations and fractures. That's why it is preferred that the catalyst support body itself not directly abuts the catalyst holding tube, but Rather, a distance from an inner shell of the first Tube portion is arranged. Accordingly, between the Catalyst support body and the inner surface of the first tube portion Retaining structures for holding the catalyst support body provided to these sufficiently in the first tube region mechanically fixing and simultaneously a transfer vibrations of the catalyst holding tube on attenuate the catalyst carrier body.

0019Such holding structures are preferably, as seen in The direction of flow of the exhaust gas, at a front end portion and a rear end portion of the catalyst carrier body provided. Preferably, between the front and rear End axial regions of the catalyst support body provided that not interposed structures are supported on the catalyst holding tube, so that at these areas, a heat transfer from the catalyst support body is reduced to the catalyst holding tube, which with respect to a more rapid attainment of the operating temperature is the catalyst advantageous. There are then only at the front and rear end portion of direct heat bridges between the catalyst carrier body and the catalyst holding tube formed by the retaining structures.

0020Such support structure is preferably through a Spacer formed, which in particular in the circumferential direction is designed to be closed to flow around the catalytic converter blocking by the exhaust gases.

0021With a view to damping of the catalyst carrier body vibrations transmitted has the standoff a Spring action on by in an area both in extending in axial and radial direction.

0022The spacer is preferably frictionally engages the inner surface the first tubular portion to. Alternatively or additionally, However, to this, on the inner surface of the first tube portion be provided a circumferential groove, into which the Standoff snaps particular when the catalytic converter is inserted into the first pipe section. alternative or in addition, is also provided, the spacer sleeve to be welded to the inner surface of the first tubular portion or soldering or joining technique in other ways connect to.

0023Alternatively or additionally, a retaining structure by a body between the catalyst carrier and the inner shell the first tubular portion inserted sleeve can be formed, which as a braid or knitted fabric or fleece or tissue or felt made of wire or other material is formed.

0024Particularly preferred is a holder in which the Holding structure of the front end portion through a spacer sleeve and the support structure at the rear end portion of the catalyst carrier body formed by a wire mesh sleeve is. This facilitates the insertion of the catalyst support body in the first tubular portion, preferably which the pipe flange near standoff with the catalyst holding tube can be welded.

0025It is further provided that radially between an in the first tube portion supporting region of the spacer sleeve and the catalyst support body a sleeve of this kind is inserted as above as directly between the first pipe section and the catalyst support body inserted Cuff described.

0026Hereinafter, embodiments of the invention based on Drawings explained in more detail. In the drawing:<dl tsize="13"><dt>figure 1</dt><dd>a schematic representation of a first embodiment management form an exhaust-gas inventive action arrangement,</dd><dt>figure 2</dt><dd>a detail view in axial longitudinal section of the in Figure 1 shown gas treatment arrangement,</dd><dt>Figure 3 to 7</dt><dd>respectively detailed views on the type of figure 2 of further embodiments of the invention Exhaust gas treatment arrangement,</dd><dt>figure 8</dt><dd>a schematic representation of yet further embodiment of the Abgasbehandlungsan- order,</dd><dt>figure 9</dt><dd>yet another embodiment of the exhaust-gas treatment arrangement and</dd><dt>figure 10</dt><dd>a detailed view of the waste shown in Figure 9 gas treatment arrangement.</dd></dl>

0027In FIG. 1, an exhaust gas treatment system 1 is schematically shown. This is used for treating exhaust gases from an Four-cylinder four-stroke internal combustion engine with a cylinder head 3 5. The cylinders of the internal combustion engine 3 is to the cylinder head intake manifold connected fresh air fed and formed during the combustion in the cylinders Exhaust gas is provided from to the cylinder head 5 Gas discharge ports 9 ejected.

0028The output by the exhaust gas discharge ports 9 flue gases be of an exhaust system 11, the exhaust gas treatment arrangement, 1 comprises, an exhaust end 13 of the given environment. The exhaust system 11 includes four Auspuffkrümmerrohre 15, each with a pipe flange 17 with an exhaust gas discharge port are screwed. 9 The four Auspuffkrümmerrohre 15 are opposite to their pipe flanges 17 Ends a pipe 19 merge with each other connected to the discharged from the four cylinders Exhaust gases in a collection tube 21 together, by means of which a flange 23 screwed to the tube reunification 19 is. The exhaust manifold 21 leads the exhaust gases through a muffler 25 of the exhaust end to. 13

0029At the pipe flange 17 adjoining pipe sections of Auspuffkrümmerrohre 15 are formed as a catalyst holding tubes 27, of which one each in its interior a catalytic converter 29 receives. Scroll through the combustion gases the exhaust gas catalysts contained in the exhaust gases harmful products of combustion into less harmful Products convert. In particular, nitrogen oxides to nitrogen reduced carbon monoxide is oxidized to carbon dioxide and hydrocarbons are oxidized to carbon dioxide and water.

0030In FIG. 2, the arrangement of the catalyst 29 in the catalyst holding tube 27 in detail. The catalyst holding tube 27 has a flange bearing the 17 first Tube portion 31, the flange 17 with the interposition a seal 33 with screws 35 fixed to the cylinder head 5 is connected. Within the first tubular portion 31 is added the catalytic 29th In an exhaust gas flow direction 37 behind the first tube section 31 is the Exhaust holding tube 27 in a second tubular portion 39 over, wherein the exhaust gases after flowing through the catalytic converter 29 leads to the pipe merge 19th The first tubular portion 31 has a larger inner diameter D1 than the second Pipe portion 39 having an inner diameter D2. The catalyst holding tube 27 with its two tube portions 31, 39 integrally formed, wherein between the two Tube portions 31, 39 a tube taper 41 is provided as a transition is.

0031The catalytic converter 29 includes a formed as a honeycomb body Catalyst support body 42, which in its Inside a plurality of schematically illustrated Flow channels 43, whose surfaces Catalyst material such as platinum and palladium, is are. The flow channels 43 have along their length in substantially the same cross section, so that the entire Catalyst support body 42 has a cylindrical shape has described the cross section as shown in FIG. 2 Embodiment is circular. The catalyst support body 42 has at its outer periphery on a coat 45th The catalyst support body 42 is formed from a ceramic material, and the shell 45 is provided on its outer surface with a Metal overlay that with a metal sleeve 47 is a joining technique firmly connected. The sleeve 47 supports the Catalyst 29 within the first tubular portion 31 in such a way that the jacket 45 at a distance A from the catalyst holding tube positioned 27th The sleeve 47 has in cross section the shape of an elongated S, where is one related to the casing 45 of the catalyst support body 42 Region 49, and a on the inner wall of the first tube portion 31 abutting portion 51 of the sleeve 47 parallel to a Axis 53 of the cylindrical catalyst support body 42 extend. Between the regions 49 and 51 extends a central region 55 of the sleeve 47, starting from the area 49 towards the flange 17 radially outward. The on the Inner shell of the first tubular portion 31 abutting portion 51 the sleeve 47 is welded to the catalyst holding tube 27, wherein a weld seam 57 indicated symbolically in FIG. 2 is.

0032On a side facing away from the flange 17 end of the catalyst carrier body 42 is provided between the jacket 45 and the inner wall the first tubular portion 31 a wire mesh sleeve 59 added that the catalyst carrier body 42 radially to the catalyst holding tube is supported.

0033For installation of the catalytic converter 29 in the catalyst holding tube 27, the sleeve 59 is first at attention on the one end of the catalyst carrier body slipped 42, then is the catalyst support body first with the cuff 59 inserted into the opening of the first tube portion 31 and so far forward that the catalyst carrier body 42 is completely accommodated in the first pipe portion 31 and a distance B between an end face of the catalyst carrier body is 42 and the pipe flange 17 is about 5 mm. Then, the weld 57 between the catalyst holding tube 27 and the area 51 of the sleeve 47 either receive all or only to a partial extent, about , Manufactured by spot welding. Thus, the catalyst carrier body 42 through the sleeve 47 in the axial direction in the fixed catalyst holding tube and both the sleeve and by the sleeve 59 in the radial direction with respect to the catalyst holding tube 27 supported.

0034Subsequently, the variants will be explained with reference to FIGS. 1 and 2 Embodiment shown. Here, components, the terms of their structure and functional components FIG. 1 and 2 correspond to the same reference numerals as indicated in FIGS. 1 and 2, to distinguish them but provided with an additional letter. Here is to the entire preceding description reference taken.

0035A in Fig. 3 in the axial longitudinal section shown catalytic converter 29a has a similar structure to that in the Fig. 1 and 2 explained the exhaust gas catalyst. Unlike For this purpose, a catalyst carrier body 42a is, however, both its front, as well as its rear end by a Sleeve 47a in a first tubular portion 31a of a catalyst holding tube 27a supported. The two sleeves 47a each have S-shaped in shape, they were both starting of on an outer casing 45a of a catalyst support body 42a moored portion 49a on an intermediate portion 55a extend radially outward and toward a pipe flange 17a and with an end portion 51a frictionally engages an inner wall the first tubular portion 31a abut.

0036This catalyst holding tube is in turn formed integrally, wherein the first tube section 31a has an inner diameter D1 which is substantially larger than an inner diameter D2 of a subsequent to the first tubular portion 31a tube portion 39a for discharging the exhaust gases. This is the first Tube portion 31a relative to the second tubular portion 39a such extended to the recorded area in the first pipe 31a Catalyst support body 42a is a cross-sectional diameter D3 which is greater than the inner diameter D2 of the second tube portion 39a.

0037A shown in FIG. 4 embodiment of the exhaust gas treatment device is similar to in Fig. 2 shown Arrangement. In contrast to this is a Pipe flange 17b opposite end of a catalyst support body 42b is not over by a wire mesh sleeve a catalyst holding tube 27b is supported, but by another metal sleeve 47b, which one of the catalyst support body 42b fixed area 49b, an after radially outward and extending away from the tube flange 17b central region 55b and a first on a pipe section 31b of the catalyst holding tube 27b frictionally abutting having area 51b. To introducing the sleeve 47b and thus the catalyst support body 42b in the first tubular section 31b to facilitate through an opening of the flange 17b, the sleeve extends 47b on the on the catalyst tube 27b abutting portion 51b also having an end portion 65 again radially inwards.

0038An embodiment shown in Figure 5. Gas treatment arrangement has a similar construction as in Fig. 3 Exhaust gas treatment arrangement shown. A catalyst support body 42c is, in turn, by at both axial ends Metal sleeves 47c supported with respect to a catalyst holding tube 27c. However, that is a pipe flange 17c of the catalyst holding tube 27c facing metal sleeve 47c with a to an inner wall of a first tube portion 31c of the catalyst holding tube 27c abutting portion 51c with the catalyst holding tube 47c 57c joined by a weld. The other metal sleeve 47c is a region 51c an inner wall of the first tube portion 31c frictionally engages. Between the area 51c 47c of metal shell and a Outer jacket 45c of a catalyst carrier body 42c is a Wire mesh cuff 59c inserted, which provided for is, vibration of the catalyst carrier body 42c within the catalyst holding tube 27c to damp.

0039An illustrated in Fig. 6 further embodiment of the exhaust gas treatment assembly has a similar construction as the explained with reference to FIG. 5, the exhaust gas treatment arrangement. In contrast, however, is a pipe flange 17d facing metal sleeve 47d for supporting a catalyst support body 42d is not a catalyst holding tube 27d welded, but simply inserted into frictional this. To further vibration damping in the two metal sleeves 47d between which at a first tubular portion 31d of the Catalyst holding tube 27d adjacent areas 51d of Metal sleeves 47d and an outer casing 45d of the catalyst support body 42d a braided metal sleeve inserted 59d.

0040Further, the first tube portion 31d passes with an inner diameter D1 is not directly in a second tube portion 39d with an inner diameter D2 on. Rather, between the two tube portions 31d, 39d, a third pipe portion 67 with an inner diameter D4 provided, which is smaller than the inside diameter D1 and larger than the inner diameter D2. At a taper 69 between the first tube section 31d and the third tube section 67 is a stop shoulder formed, at which the remote from the pipe flange 17d Sheet metal sleeve 47d comes to rest, a slippage of the catalyst support body 42 in the catalyst holding tube 27d into to prevent.

0041An embodiment shown in Fig. 7 of the waste gas processing installation has a similar construction as the reference the Fig. 6 embodiment explained. In contrast, has a first tubular portion 31e of a catalyst holding tube 27e a circumferential groove 71 in which a metal sleeve 47e for supporting a catalyst carrier body 42e opposite the first pipe section 31e with a range 51e engaged is to the catalyst carrier body 42e in both direction in the catalyst holding tube 27e in this, as well as in the opposite direction axially set.

0042A shown in FIG. 8 gas treatment arrangement 1f has a similar construction as the reference to FIG. 1 and 2 explained exhaust gas treatment arrangement. Unlike However, this is a front face of the catalyst carrier bodies 42f not substantially directly to exhaust discharge ports 9f arranged. Rather, these Faces B of the exhaust gas discharge ports at a distance of about 20 cm.

0043An exhaust gas treatment arrangement, shown schematically in Fig. 9 1G has a construction to that shown in Fig. 8 Exhaust gas treatment arrangement is similar. Here are front end surfaces of catalytic converters with a 29g increased distance B of about 30 cm from the exhaust gas discharge ports 9g of a cylinder head 5g arranged. However, a each catalytic converter 29g not separately a single exhaust gas discharge port assigned 9g. Rather, each catalytic converter 29g a group of two exhaust gas discharge ports assigned 9g. Here, between a first tube section a catalyst holding tube 27g, in which the exhaust gas catalyst 29g is added, and pipe flanges 17g which are screwed to the exhaust gas discharge openings 9g, a pipe-gathering 75 arranged for the exhaust gases from two exhaust gas discharge ports 9g an exhaust gas catalyst feed 29g.

0044To the first tube portions 31g into which the exhaust gas catalysts 29g are added to second pipe section close 39g of the catalyst holding tube 27g to which a another pipe reunification 19g open to the exhaust fumes of all four cylinders of the engine 5g to a common manifold merge 21g.

0045As shown in Fig. 10, the first tube portion 31g and the second tube portion 39g of a turn single piece of pipe manufactured. The tube 75 is merging welded to the first pipe portion 31g with a weld 77, which was made after the catalyst carrier body 42g was inserted into the first pipe section.

0046In the embodiments described above is the Catalyst support body, a ceramic catalyst carrier body, is what metallized on its outer jacket to because a metal sleeve for supporting the catalyst support body Fasten metallurgically in the catalyst holding tube to. However, it is also possible for the catalyst support body not be made of a ceramic material, but of a metal material, in which case the fastening the metal shell is simplified.

0047In the embodiments described above was further uses a wire mesh sleeve to the catalyst support body vibration absorption to the catalyst holding tube support. Deviating from this function but not limited to a wire mesh sleeve. Rather, other seals may be provided, such as for example, knitted or woven fabrics of wires, tapes, etc., which also does not have to be made of metal necessarily may include and about mineral fibers or the like.

0048In the embodiments described above is in each case in the first region of the catalyst holding tube in each case a single catalyst carrier body disposed. However, it is also possible in the first pipe section more arranging the catalyst support body, in particular axial succession.