DD296990A5 - DEVICE FOR CATALYTIC DETOXIFICATION OR DGL. OF COMBUSTION ENGINE EXHAUST GASES WITH DOUBLE-WALL HOUSING - Google Patents

Abstract

Device for catalytic detoxification, for the extraction and / or silencing of internal combustion engine exhaust gases, having a housing * which has two open end regions (12) connected to an exhaust gas line (18) and a passage for the exhaust gas between the end regions (12), wherein the housing (2) at least in a portion of its length a Auszenschale * an inner shell (6) and an insulating mat (8) between them. The plunger shell (4) and the inner shell (6) are connected to each other by elastic retaining elements (10) of compressed wire mesh or wire mesh and otherwise substantially without mutual metallic contact. Fig. 1 {detoxification; Catalyst; Entruszung; Silencer; Internal combustion engine; exhaust gas; Casing; Inner shell; insulating; Auszenschale; Retaining element, elastic}

Description

For this 3 pages drawings

The invention relates to a device for catalytic) decontamination, for decloaking and / or silencing of engine exhaust gases, with a housing having two open, connected to an exhaust pipe end portions and a flow passage for the exhaust gas between the end portions, wherein the Housing at least in a portion of its length has an outer shell, an inner shell and an insulating mat in between. An apparatus of this type is known in the case of catalytic detoxification of engine exhaust gases. In this device, the idea is based on avoiding an action on the outer shell with the hot exhaust gases. For this purpose, the existing of high temperature resistant steel sheet inner shell was provided. As a result, the outer shell, which fulfills the supporting function, can consist of less temperature-resistant and therefore less expensive sheet steel. Between the outer shell and the inner shell there is a metallic contact or a metallic connection in the end regions of the housing and / or in the vicinity of the end surfaces of the catalytically coated monolith installed in the housing.

In connection with the work on the invention has been found that in the known construction of the sound generated in the interior of the device by the pulsating engine exhaust, in particular on the inner shell and on the housing internals, such as the catalytically coated monolith, largely to the Outer shell is transferred. The device therefore emits sound via its outer shell with considerable sound pressure.

The invention has for its object to make available a device of the type mentioned, which has a lower sound emission while maintaining the basic advantages of the clam shell construction. To solve this problem, the device according to the invention is characterized in that the outer shell and the inner shell are connected by elastic holding elements of compressed wire mesh or wire mesh and otherwise substantially without mutual metallic contact.

The holding elements create despite the different thermal expansion of outer shell and inner shell a permanent connection between these components. This compound is less schalleitend than a flat metal / metal compound. Preferably, the outer shell is fixed without direct attachment to the exhaust pipe on the inner shell, in particular determined by the holding elements. Alternatively, however, it is possible to attach the outer shell conventionally to the exhaust pipe, because this is a sound source to a lesser extent than the internals of the device housing. Further, it is possible to store the outer shell with the interposition of elastic holding elements of compressed wire mesh or wire mesh on the exhaust pipe. When it is spoken of "the outer shell", this also analog outer shell sections are to be understood when the outer shell is divided in length into several sections.

Preferably, at least one of the holding elements is continuous annular or composed of part-holding elements annular. In principle, one could also work with circumferentially distributed, separate holding elements. However, this is not particularly favorable from an assembly point of view.

Preferably, at least one of the holding elements is fixed positively in the axial direction and / or in the circumferential direction, on the outer shell and / or the inner shell. Particularly preferred means for the positive fixing are suitable beads which form on the outer shell by bulging outward or on the inner shell by bulging inward fixing spaces for the holding element or the holding elements. The opposite variant, ie positive clamping by bead-like impression on the inside of the outer shell or by bead-like expression on the outside of the inner shell, is possible. For fixing in the axial direction, the beads normally run in the circumferential direction. For definition in the circumferential direction, the beads normally extend in the axial direction. But there are also mixed forms possible, for example, locally limited manifestations or indentations on the outer shell or on the inner shell, which-distributed to a plurality of circumferentially -both a determination in the axial direction as well as a determination in the circumferential direction. Further below, a particularly preferred embodiment is described in which due to the structure of the inner shell and the outer shell of welded half-shells receiving spaces or projections arise that define the retaining element form-fit in the circumferential direction similar to an axially extending bead. A particularly stable, manufacturing and assembly-favorable fixing of the holding element results when this is composed of two substantially semi-annular part-holding elements, of which at least one is radially thickened at least at one circumferential end and with the thickened circumferential end in a bulge of the outer shell and / or the inner shell is received. This thickening can be generated in particular by compressing the respective circumferential end or by folding the circumferential end. The latter possibility can be realized, in particular, by producing one or both circumferential ends of the semi-annular part-holding element with a radially protruding nose, which continues to fold over during assembly.

It is possible to form at least one of the holding elements with progressive spring stiffness in the radial direction, in particular by means of a profile suitable for this purpose in longitudinal section - for example trapezoidal or triangular profile - or by training as a wire mesh tube or wire mesh tube which becomes stiffer after cavity compression against further deformation.

Preferably, a holding element is provided at least in one of the two end regions of the housing. This creates a favorable fixing of the outer shell, wherein in the central region of the insulating mat can cause a less strict, but sufficient determination.

Preferably, at least one housing end region for sealing the annular space between the outer shell and the inner shell, a radially narrow gap between the outer shell and the inner shell or the outer shell end cross-scenery link ring or a sealing ring or a sealing formation of the annular retaining element is provided. It should preferably be avoided that water or dirt from the outside enters the said annulus. Preferably, in at least one of the holding elements an axially-relatively movable connection to the outer shell or the inner shell is provided. In this way, differences in thermal expansion between the very hot inner shell and the cooler outer shell can be absorbed.

Preferably, one or more ceramic monoliths with catalytic coating are (are) held in the housing one or in axial succession, either in the inner shell or in the inner shell in the outer shell when the inner shell is interrupted. It is understood that the term "in the inner shell" also includes the standard case that around these still comes the outer shell, so that the monolith is supported there in the double-shell housing.

The term "at least one of the holding elements" has been used several times in the claims and in the preceding description.This way of expression relates primarily to ring-shaped holding elements If a plurality of separate holding elements are provided on the circumference in a cross-sectional plane, the corresponding statement for the The statement in question applies to several or even all the holding elements in several cross-sectional planes.

Particularly preferred is the following configuration: The outer shell extends over the entire length of the device housing and is connected at both ends by means of annular or annular composite holding elements with the inner shell, wherein at one end a sliding seat between the outer shell and inner shell is present. The inner shell can also pass through or be subdivided over the entire length of the housing, wherein it leads at least in each case from the relevant exhaust-pipe end to at least close to the-or one-of the monoliths contained in the housing.

In the foregoing, catalytically coated monoliths have been mentioned in several places. Instead, in the housing of the device filter body for emptying the exhaust gas of diesel engines may be present, for example in the form of porous ceramic body or in the form of metallic, sieve-like trained body. Finally, in the housing internals similar to conventional exhaust mufflers may be present. In all these cases, the issue of the lowest possible sound emission turns outward.

The core idea of the invention is the avoidance of sound bridges between the primarily sound-radiating components and the outer shell, wherein the latter should nevertheless be reliably supported on the overall arrangement.

It is expressly understood that the features specified in the subclaims 2 to 12 are partly technically feasible in their own right, that is, without including at least the features of claim 1. This is particularly true for the claims 3, 5, 6,7, 8 (positive fixing of an annular or composed of part-holding elements annular retaining element in the circumferential direction).

The invention and embodiments of the invention will be explained in more detail below with reference to preferred, illustrated embodiments. Show it

Fig. 1: an exhaust gas device in longitudinal section;

Fig. 2 to 5: sections of exhaust gas devices in longitudinal section;

Fig. 6: an attached holding element in cross-section and on an enlarged scale;

FIG. 7: a partial holding element from FIG. 6 in the state before installation and in comparison with FIG. 6 on a smaller scale; FIG.

Fig. 8: a part of another exhaust gas device in longitudinal section, namely two variants.

The exhaust device shown in Figure 1 comprises a housing 2 which consists essentially of a longitudinally continuous outer shell 4, a longitudinally continuous inner shell 6, a longitudinally continuous insulating mat 8 between the outer shell 4 and the inner shell 6 and annular retaining elements 10, which are each arranged in an end region 12 of the housing 2 between the outer shell 4 and the inner shell 6. In the housing 2, two monoliths 14 of porous ceramic material and with catalytic coating are arranged axially one behind the other, in each case supported in the inner shell 6 by means of a support mat 16. The left in Fig. 1 end portion 12 is connected to an open end of an exhaust pipe 18, and the right in Fig. 1 end portion 12 is also connected to an open end of the exhaust pipe 18, so that the device bridges a distance between the two said ends of the exhaust pipe 18. The exhaust gas of an unillustrated internal combustion engine flows through the device in the direction of arrows P, wherein an exhaust gas flow passage leads longitudinally through the housing 2 from the left end portion 12 to the right end portion 12 and through the two monoliths 14. The inner cross-sectional area of the inner shell 6 increases in each case from the end region 12 in the direction of the region where a monolith 14 is arranged. Overall, the cross-sectional shape of the housing 2, for example, is substantially circular or elliptical.

The inner shell is preferably made of stainless, high temperature resistant steel sheet. The outer shell 4 is preferably made of less highly alloyed steel. The holding elements 10 are compressed wire knit rings or Drahtgeweberinge, wherein the wire is preferably stainless and high temperature resistant. The insulating mat 8 is preferably made of ceramic fibers or is a commercially available, so-called. Quellmatte that increases in volume when heated to significant temperatures. The support mat 16 is preferably made of compressed wire mesh with the wire used being stainless and high temperature resistant.

The left retaining ring 10 is received on Außenumfnag in a circumferential bead 20 of the outer shell 4. The same applies to the right retaining ring 10. The left retaining ring 10 is added to the inner circumference in a peripheral bead of the inner shell 6 or - in other words-between two axially spaced, outwardly embossed beads of the inner shell 6 set. When right retaining ring 10, the inner shell 6 has a bead-free outer circumference. At the right end portion 12 and the left end portion 12, the inner shell 6 is welded to the exhaust pipe 18. By the described attachment of the left retaining ring 10, the outer shell 4 and the inner shell 6 are connected to each other there in such a way that they can not move against each other in the axial direction. In the right end portion 12, an axial relative displacement between the outer shell 4 and the inner shell 6 is possible because the local retaining ring 10 can move on the inner shell 6. It can be seen that the outer shell 4 and the inner shell β are interconnected only via the two retaining rings 10 and the insulating mat 8. Due to this type of connection structure-borne noise of the inner shell 6 is transmitted only attenuated to the outer shell 4. The retaining rings 10 are installed with elastic, radial bias. They retain their elasticity permanently.

The support mats 16 are folded over in their axial end portions doppeldend and each surround the edge of the end faces of the monoliths 14. The support mats 16 are installed with bias. In the right support mat 16 can be seen in the axial center of an inserted sealing ring 22 made of suitable, temperature-resistant material. Furthermore, it can be seen in Fig. 1, that the inner shell 6 in the areas where a monolith 14 is supported, outwardly embossed, circumferential beads and has been retracted at the end faces of the monoliths 14 a piece inward, so that in this way the Monoliths 14 are reliably fixed. The outer shell 4 has at the same points inwardly embossed, circumferential beads, so that in this way the insulating mat 8 is reliably fixed.

The greater thermal expansion of the inner shell 6 compared to the monoliths 14 are absorbed by the support mats 16. Different thermal expansions between the inner shell 6 and the outer shell 4 are absorbed by the described sliding fit between the right retaining ring 10 and the inner shell 6.

The fnnenschate 6 is the main component of the housing 2. Due to the radial distance between the inner shell 6 and the outer shell 4 and as a result of the insulating mat 8 in between the outer shell 4 is not particularly hot. In addition, the monoliths 14 reach their "light-off temperature" for the catalytic exhaust gas detoxification particularly quickly because the heat losses through the housing 2 are reduced.

Instead of the monoliths 14 described, soot filters or sound-damping internals may also be provided in the housing 2. Even with soot filters, the reduced heat loss to the outside is advantageous because the required burn-off temperature is reached sooner or more frequently.

Both the inner shell 6 and the outer shell 4 consist - which is not recognizable from the drawing - from two half-shell parts, which are welded together by two longitudinal welds.

2 and 3 show variants of retaining rings 10, which have a progressive spring hardness in radial compression. In the case of the retaining ring 10 according to FIG. 2, this is achieved by a configuration that is trapezoidal in section. The retaining ring 10 according to FIG. 3 has a tube-like configuration; During radial compression, the deformation resistance increases steeply from the flat pressing of the tubing.

Figure 4 illustrates that one can fix the retaining ring 10 instead of a bead by circumferentially welded to the inner shell 6 metal strips or wires form-fitting manner. The same possibility exists for the positive fixing in the outer shell 4, which is not shown in the drawing.

From FIGS. 1 to 3 it can be seen that the annular space between the inner shell 6 and the outer shell 4 is open at the front. In order to avoid excessive penetration of dirt or water there, as shown in FIG. 4, this end gap may be covered by a slide ring 26 fastened to the exhaust pipe 18. An alternative possibility is to omit the slide ring 26 and bring the end of the outer shell 4 radially as closely as possible to the exhaust pipe 18 and and also make this overlap region axially long enough.

By Fig. 5 illustrates that the beads 20 on the inner shell 6 need not be circumferential, but may consist of a series of circumferentially spaced forms 28. As a result, in addition to a positive fixing in the axial direction and a positive fixing of the retaining ring 10 is achieved in the circumferential direction. The same possibility exists for fixing the retaining ring 10 in the outer shell 4 (not shown in the drawing). In Fig. 5, the exhaust pipe 18 is not shown for reasons of clarity.

FIGS. 6 and 7 show a special holding element 10 composed of two partial holding elements 10 a and 10 b. Each partial holding element 10a or 10b is substantially semi-annular. In the pre-installation state (see Fig. 7), each part-holding member 10a and 10b is substantially rectilinear with a for-supporting nose 30 at each end. During installation, the lugs 30 are pushed back in the circumferential direction and result in a local, radial dimensioning doubling of the partial holding element 10a or 10b. This radially thickened region is received in a corresponding bulge 32 of the outer shell 4. The outer boundary 34 to be stretched when the noses 10 are folded back during assembly is rounded and nestles against a corresponding curvature of the inner shell 4 in the region near a weld seam 36, by which two inner shell halves are welded together. In Fig. 6 can be seen well the structure of the outer shell 4 and the inner shell 6 each of two half-shells welded together. In Figure 6 is further indicated by at the peripheral ends of the two part-holding elements 10a and 10b dense hatching that at these circumferential ends of the metal mesh or the metal fabric is more compacted. Due to the described construction and assembly of the part-holding elements 10a and 10b, a very stable, form-fitting fixing of the overall holding element 10 in the circumferential direction is achieved. In many cases, however, it is sufficient to determine the holding elements in a simpler manner in the circumferential direction, for example, by axially extending beads or by the described in connection with FIG. 5, local characteristics. It is also possible to fix the holding elements 10 by spot welding on the outer shell 4 or the inner shell 6, which naturally means at the same time an axial fixing and a determination in the circumferential direction.

By Fig. 8 illustrates that the inner shell 6 does not necessarily have to go through the length of the housing 2. Fig. 8 shows a variant in which the inner shell 6 is divided and is provided separately both in the inflow funnel and in the outflow funnel. In the variant of Fig. 8, above, is the left retaining ring 10 in the end portion 12 of the housing 2 between the inner shell 6 and the outer shell 4. The left retaining ring 10 is fixed positively in the outer shell 4 in the axial direction. The local end of the partial inner shell 6 is received with Schiebesiu between the retaining ring 10 and the outer periphery of the end portion of the exhaust pipe 18. The local end of the outer shell 4 is brought to the outer circumference of the exhaust pipe 18 and welded to this. The right in Fig. 8 retaining ring 10 is located just before the end face of the monolith 14. The right in Fig. 8 end portion of the inner shell 6 is clamped on the outer periphery of the monolith 14. The circumferential bead 20 of the inner shell 6 also forms a stop for the front edge of the monolith 14. It can be seen again an insulating mat 8 between the inner shell 6 and the outer shell 4 and a support mat 16 between the outer periphery of the monolith 14 and this time the outer shell ,

The variant of Fig. 8, below, differs from the variant just described in that the inner shell 6 is welded to the left with the exhaust pipe 18 and right ends just before the monolith 14. The outer shell 4 is not welded to the left side of the exhaust pipe 18. The right retaining ring 10 rests against both the inner shell 6 and the monolith 14 inside. In addition to the embodiment of Fig. 4 is added that for the sealing of the annular space 24 between the outer shell 4 and the inner shell 6, alternatively, a superior sealing ring or a penetration of the retaining ring 10 with sealing effect-producing substances is possible.

It should be noted that the exhaust gas device can also be performed with only a monolith 14 or soot filter and that it is possible, a mehrflutige, in particular double-flow, execution with z. B. two monoliths 14 next to each other and to build according to a substantial 8-shaped housing 2. The central axis of the exhaust pipe 18 need not be aligned with the central axis of the monoliths 14.

Claims (12)

1. Device for catalytic! Detoxification, for the extraction and / or silencing of internal combustion engine exhaust gases, comprising a housing (2) having two open, connected to an exhaust pipe (18) end portions (12) and a flow passage for the exhaust gas between the end regions (12), wherein the housing (2) has at least in a partial region of its length an outer shell (4), an inner shell (6) and an insulating mat (8) between them, characterized in that the outer shell (4) and the inner shell (6) by elastic retaining elements (10) are made of compressed wire mesh or wire mesh and are otherwise connected together substantially without mutual metallic contact. 2. Apparatus according to claim 1, characterized in that the outer shell (4) is fixed without direct attachment to the exhaust pipe (18) on the inner shell (6). 3. Apparatus according to claim 1 or 2, characterized in that at least one of the holding elements (10) is continuous annular or composed of part-holding elements is annular. 4. Device according to one of claims 1 to 3, characterized in that at least one of the holding elements (10) in the axial direction positively to the outer shell (4) and / or the inner shell (6) is fixed. 5. Device according to one of claims 1 to 4, characterized in that at least one of the plurality of holding elements (10) is positively fixed in the circumferential direction. 6. Apparatus according to claim 5, characterized in that the fixed in the circumferential direction holding element (10) consists of two substantially semi-annular part-holding elements (10 a, 10 b) is composed, of which at least one is radially thickened at least one circumferential end and thickened with the Peripheral end (30) is received in a recess (32) of the outer shell (4) and / or the inner shell. 7. Apparatus according to claim 6, characterized in that the thickening is formed by folding the peripheral end. 8. Device according to one of claims 1 to 7, characterized in that at least one of the holding elements (10) has a progressive spring hardness in the radial direction. 9. Device according to one of claims 1 to 8, characterized in that a holding element (10) is provided at least in one of the two end regions (12) of the housing (2). 10. Device according to one of claims 1 to 9, characterized in that at least one housing end region (12) for sealing the annular space between the outer shell (4) and the inner shell (6) has a radially narrow gap between the outer shell (4) and the Inner shell (6) or the outer shell end cross-cam slide ring (26) or a sealing ring or a sealing construction of the annular retaining element (10) is provided. 11. Device according to one of claims 1 to 10, characterized in that at least one of the holding elements (10) is provided an axially-relatively movable connection to the outer shell (4) or the inner shell (6). 12. Device according to one of claims 1 to 11, characterized in that in the housing (2) one or axially successively a plurality of ceramic monoliths (14) are supported with catalytic coating, either in the inner shell (6) or in broken inner shell (6) in the outer shell (4).