EP0635626A1 - Exhaust gas converter - Google Patents

Abstract

Exhaust gas converter with at least one monolith (2) composed of a plurality of individual ceramic elements (1), the individual elements (1) being covered on their contact surfaces with expanded material (4, 5, 20) and the expanded matting material (4, 5, 20), in operation of the converter, bracing the individual elements (1) to form a monolithic block. <IMAGE>

Description

To reduce pollutants in exhaust gases from internal combustion engines, in particular for motor vehicles, it is known to use exhaust gas converters. Such exhaust gas converters consist of a housing and one or more monoliths made of ceramic material embedded in the housing. With these exhaust gas converters, several monoliths are connected in series or in series. This means that several monoliths are arranged one behind the other in the direction of the exhaust gas flow. The exhaust gas stream must flow through several monoliths one after the other in the exhaust gas flow direction. When flowing through the monoliths connected in series, more and more pollutants are removed from the exhaust gas stream until the exhaust gas stream is cleaned so that it can be passed on to the environment by the exhaust gas system.

Exhaust gas converters, as well as the entire exhaust system, are usually arranged in the area of the floor pan of a vehicle. As a result of this arrangement in the area of the floor assembly, only a very limited installation space, which is often problematic in terms of its geometry, is specified. As a result of the installation space specified with regard to its cross section and its dimensions, it is not possible to manufacture the monolith in one piece. The monolith made of ceramic material can often no longer be easily extruded or fired in the required large numbers.

Exhaust gas converters for engines with larger displacements have therefore started to assemble the monoliths from several elements. The elements each have a simple and smaller surface cross-section and can be assembled into large-volume monoliths with more complex cross-sectional shapes. As is known, the elements are firmly connected to one another when the monolith is assembled using appropriate adhesives. A disadvantage of this solution is considered that an adhesive must be used at all. This glue usually has to have a high temperature resistance in order to keep the monolith securely together even at high exhaust gas temperatures. In addition, it must be ensured that the physical properties of the adhesive are well coordinated with the material characteristics of the carrier material and that the adhesive is environmentally friendly.

Based on these disadvantages, the invention has for its object to design an exhaust gas converter so that the monolith or monoliths therein can be assembled from individual elements without the use of adhesive. This object is achieved by the combination of features of claim 1.

The monolith block is also composed of several individual elements in the exhaust gas converter according to claim 1. The individual elements continue to form the monolith block. To form the monolith block, the individual elements are arranged in parallel, so to speak, side by side. The monolith is put together like a puzzle from individual elements. The individual elements are at least partially covered with swelling mat material on their outer surfaces. In the case of monoliths lying in the converter housing, the source mat material swells as a result of heat during operation of the exhaust system and, as it were, braces the individual elements against one another. The source mat material fixes the individual elements in the converter housing with a clamp.

To assemble the exhaust gas converter, the monolith block wrapped with source mat material is inserted into an exhaust gas converter housing, preferably made of sheet metal, and the housing is closed. This converter housing can consist, for example, of two half-shells, which are provided with transverse beads, in order to be able to connect several monolith blocks in series. The half-shells are flanged at their opening edges to form welding rims. The half shells are simply welded together in the area of their welding rims for the final assembly of the converter housing.

It is also conceivable to wind the housing from a sheet metal strip in the so-called winding construction. Here, a sheet metal strip or sheet is simply wrapped around the circumferential surface of the monolith block wrapped with the continuous swelling mat and for example by soldering or Welding closed to the converter housing. Finally, it is also possible to use a converter housing based on the funnel design. Here, the monolith or the series-connected monoliths are introduced into a cylindrical tube. The cylindrical tube is then welded in the region of its opening edges with funnel-shaped closures. The lines of the exhaust system can be connected to the sides of the funnels which face away from the cylinder receiving the monolith.

As a result of the process heat occurring during the operation of the exhaust gas converter, the source mat inflates to a certain extent and effectively clamps the monolith in the converter housing. Such swelling mats are also known from the prior art.

The dual function of the source mat is advantageous in the embodiment according to claim 2 as a holding part of the individual elements forming the monolith block during assembly and as a clamping part for the monolith block after installation and during operation of the exhaust gas converter.

Claims 3 and 4 relate to further embodiments of the above-described invention which are improved with regard to their usage properties. According to claim 3, source mat blanks are also introduced into the parting lines between the adjacent contact surfaces of the individual elements. These source mat blanks also swell due to the process heat during the operation of the exhaust gas converter and have an additional clamping effect with respect to the individual elements forming the monolith. This measure has the effect that the individual element does not leave its relative target position with respect to one another even during operation of the exhaust gas converter, in particular when subjected to shock and shock. The measures therefore serve to maintain the structure of the monolith block.

The installation of continuous element swell mats completely enclosing the elements is technically favorable in terms of assembly. The individual elements can simply be pushed into the element source mats and thus pre-assembled into assemblies. The assemblies preassembled in this way are simply brought into their desired position with respect to one another in a second work step and finally wrapped with the continuous swelling mat wrapping the outer peripheral surface of the monolith block.

The embodiment according to claim 4, on the other hand, also makes it possible to form the monolith block by inserting two individual elements wrapped around with an element source mat in a housing half-shell and then closing the housing half-shell. In this embodiment, the housing half-shell assumes the cohesion function in the monolith assembly. In the final assembly state, the element swell mats each swell and clamp the individual elements in the converter housing in such a way that the individual elements form a solid and secure block structure.

Claim 5 relates to a preferred order of magnitude of the basis weight of the source mat material.

The optional claims 6 to 14 referring to claims 1 to 5 relate to a further, inventive embodiment of the present invention. In the final assembly state, there is a risk in the inventive design of the monolith that the source mat and / or the source mat cuts and / or the element source mats in the region of their end faces are eroded by the gas stream and detached in particles from the monolith block. So there is a latent risk of swelling of the source mat.

The further, inventive embodiment of the converter is therefore based on the task of designing a monolith for exhaust gas converters in such a way that it can be assembled from individual elements without adhesive and, at the same time, erosion of the source mat material in the region of the front edges is effectively prevented. To solve this problem, it is proposed to arrange protective profiles in the area of the front edges. These protective profiles are intended to effectively shield the separating joints between the individual elements, which are covered with swelling mat material, against the exhaust gas flow and thus prevent erosion of the swelling mat material.

Claims 7 to 12 relate to a basic embodiment of the protective profiles, claims 13 and 14 an alternative basic embodiment. According to claim 7, the protective profiles are designed as T-shaped profile pieces. The T-shaped profile pieces lie with their T-base in the parting lines formed between the contact surfaces of two individual elements and are held in place by the swelling mat material also lying in the parting line area. The source mat material is therefore not only used to secure the position of the individual elements of the monolith but in addition to the storage of the T-shaped protective profiles. Claims 8 and 9 relate to advantageous dimensions of the T-shaped profile pieces. The dimensioning of the T-shaped profile pieces according to claim 10 ensures economical use of the profile material on the one hand and an effective shielding of the joints against the exhaust gas flow on the other.

Claims 11 and 12 relate to the simple use of profile angles for producing the T-shaped profile pieces. For this purpose, the profile angles each have profile legs that are at right angles to one another. The profile angles are mirror-inverted with two profile legs fixed to each other in such a way that the profile legs that do not lie against each other on the same side to form the T-legs project from the base formed by the two legs lying against each other. The profile brackets can either be pushed individually into the parting lines in order to be clamped against one another by the pressure of the source mat material in the final assembly state. On the other hand, it is also possible, according to claim 12, to connect the adjoining profile legs which form the T base, in order to prefabricate a T profile.

As an alternative to the T-profiles, claims 13 and 14 relate to a cover frame preferably drawn from sheet steel. The cover frame consists of profile struts which, according to this second embodiment, replace the T-profiles according to the above-described first embodiment or, if necessary, supplement them in a basic form. The profile struts form a skeletal structure. This skeletal structure corresponds to the structure of the line formed by the parting lines in the area of the end face of the monolith. The frame formed as a molded part can be easily pushed onto the front of the monolith. It is particularly advantageous to design the struts in such a way that in the final assembly state the struts nestle particularly well against the end faces of the joints and in this way effectively prevent the exhaust gases from penetrating into the joints. The use of the frame designed as a molded part is particularly suitable for large series production because it is much easier in terms of assembly technology to place a single frame on the end face of the monolith, while in the first embodiment a plurality of T-shaped profile pieces are placed in the end face of the monolith must be introduced.

To make assembly of the frame even easier, the front structure can be of the monolith can be designed asymmetrically in order to allow only one mounting position of the frame. For better protection against the effects of exhaust gases, it is advantageous to additionally soak the end edges of the swelling mat in the parting lines with a binding agent made of glass and / or plastic and thus to strengthen them.

An important advantage of the invention is that both the individual elements forming the monolith block and the monolith block as a whole can assume any desired geometrical figures and cross-sectional shapes. With the inventions it is therefore possible to manufacture exhaust gas converters in any shape and structure.

Fig. 1

eine Draufsicht auf die Stirnseite eines Monolithen,

Fig. 2

eine Darstellung des Schnitts II-II in Fig. 1,

Fig. 3

eine Draufsicht auf die Stirnseite eines Abgaskonverters gemäß einer weiteren, alternativen Ausführungsform zur Ausführungsform gemäß Fig. 1,

Fig. 4

eine Darstellung des Schnitts IV-IV in Fig. 3,

Fig. 5

eine Draufsicht auf einen auf die Stirnseite des Monolithen aufzusetzenden Abdeckrahmen,

Fig. 6

eine Darstellung des Schnitts VI-VI in Fig. 5.

The inventions are explained on the basis of the exemplary embodiments illustrated in the drawing figures with further advantages and features. Show it:

Fig. 1

a plan view of the end face of a monolith,

Fig. 2

a representation of the section II-II in Fig. 1,

Fig. 3

2 shows a top view of the end face of an exhaust gas converter according to a further alternative embodiment to the embodiment according to FIG. 1,

Fig. 4

a representation of the section IV-IV in Fig. 3,

Fig. 5

2 shows a plan view of a cover frame to be placed on the end face of the monolith,

Fig. 6

a representation of the section VI-VI in Fig. 5th

FIG. 1 shows the monoliths 2 composed of six individual ceramic elements 1. The individual elements in the monolith 2 shown in FIG. 1 are put together in segments. The separating joints 3 are arranged between the individual segment-shaped individual elements 1. However, the individual elements 1 do not lie against one another with their contact surfaces in the separating joints 3. In the embodiment shown in FIG. 1, a swelling mat blank 4 is in each case fixed on the contact surfaces of the individual elements 1. Each parting line 3 is therefore filled by means of two swellable mat cuts 4. The individual elements 1 with their source mat blanks 4 consequently lie against one another. The outer contour of the monolith 2 formed from the individual elements 1 is completely enclosed by the continuous swelling mat 5. The swelling mat 5 thus forms a circle around the monolith 2 shown in FIG. 1.

The ceramic individual elements 1 are provided between the parting lines 3 with openings - here segmented in FIG. 1. The exhaust gas stream flows through these openings during operation of the exhaust gas converter. The exhaust gas flow therefore flows perpendicular to the plane of the drawing in FIG. 1. Finally, the converter housing consisting of two half-shells 6 can be seen in FIG. The two half-shells 6 forming the converter housing are welded to one another in the region of the flanged welding rims 7.

FIG. 2 again shows, according to section II-II in FIG. 1, two adjacent ceramic individual elements 1, the parting line 3 arranged between the adjacent individual ceramic elements 1 and the swelling mat cuts 4 lying in the dividing line 3. The T is between the swelling mat cuts 4 -shaped profile piece 10 introduced. The T-shaped profile piece 10 consists of the T-base 11 lying between the source mat blanks 4 and the two T-legs 12 running at right angles to the T-base 11. In the final assembly state, the two T-legs 12 cover the entire width of the parting line 3 in the spacing direction 13. The profile piece 10 is clamped with its T-base 11 between the source mat blanks 4. The source mat blanks 4 clamp the T base 11 between them over the distance of the clamping depth 14 of the T base 11. The clamping depth 14 corresponds to the area of the T base 11 lying between the source mat blanks 4.

From Fig. 2 it can also be seen that the T-shaped profile piece 10 is composed of two rectangular profile angles 15. The profile angles 15 are arranged mirror-symmetrically to one another with respect to the axis of symmetry 16. One leg of a profile angle 15 forms a T-leg 12, while the other leg forms half of the T-base 11.

3 again shows a housing welded together from two half-shells 6 in the area of the welding rims 7. The two semicircular ceramic individual elements 1 lie in the housing. Each of the individual ceramic elements 1 is wrapped by a continuous element source mat 20. The parting line 3 between the individual elements 1 forming the monoliths 2 is also filled by the corresponding areas of the element source mat 20. The illustration in FIG. 4 corresponding to the illustration in FIG. 2 again shows the substitution of the source mat blanks 4 in FIG. 2 by the corresponding regions of the element source mats 20 in FIG. 4.

In the embodiment according to FIG. 3, a swelling mat 5 surrounding the entire monolith 2 may also be present, but not shown in FIG. 3. In the exemplary embodiment shown in FIG. 3, the ceramic individual elements surrounded by the element source mats 20 are placed in a half shell 6 and the half shell 6 is completed by welding to the second half shell 6 to form the converter housing. The element source mats 20 clamp the monolith 2 in the operating state in the converter housing.

FIG. 5 shows the frame 25 that can be placed on the end face of the monolith according to FIG. 3. The frame 25 consists of the profile struts 26 and the openings 27 arranged between the profile struts for the passage of the exhaust gas flow perpendicular to the plane of the drawing in FIG. 3 or FIG. 5. From Fig. 3 and Fig. 5 it can be seen that the contour of the frame 25 is adapted to the contour of the end face of the monolith 2. As a result of this complementary design of frame 25 and monolith 2, frame 25 can easily be placed on the end face of monolith 2 shown in FIG. 3.

Fig. 6 shows the profile of the frame 25 according to section VI-VI. For this purpose, the profile struts 26 are flanged in a bowl shape in cross section. As a result of this flanging, the profile struts 26 have an essentially U-shaped cross section with the U-legs 28.

The cross section of the profile struts 26 with the U-legs 28 is again clearly visible in FIG. 4. From the illustration in FIG. 4, it can also be seen that the area of the profile strut 26 arranged between the U-legs 28 protrudes slightly into the parting line 3 when the profile strut 26 is placed in the mounting direction 30 onto the parting line 3. In other words, the profile strut 26 is flush with the parting line edges 31 when the profile strut 26 is attached in the mounting direction 30. The area of the profile strut 26 between the parting line edges 31 protrudes a bit into the parting line 3 in the mounting direction, so that penetration of the exhaust gases into the parting line and erosion of the source mat material of the element source mats 20 is effectively prevented.

Reference list

1

Single ceramic element

2nd

monolith

3rd

Parting line

4th

Source mat cutting

5

Swelling mat

6

Half shell

7

Welding shelves

10th

Profile piece

11

T base

12th

T-leg

13

Distance direction

14

Clamping depth

15

Profile angle

16

Axis of symmetry

20th

Element source mat

25th

frame

26

Profile strut

27

opening

28

U-leg

30th

Direction of touchdown

31

Joint edge

Claims (14)

Exhaust gas converter with at least one monolith block (2) composed of several individual elements (1),
characterized, - That the individual elements (1) are at least partially covered with swelling mat material (4, 5, 20) on their contact surfaces and - That the source mat material (4,5,20) braced the individual elements (1) in converter operation to form a monolith block (2). Exhaust gas converter according to claim 1,
characterized,
that the outer circumferential surface of the monolith block (2) is wrapped by a one-piece continuous swelling mat (5, 20) which holds the individual elements (1) together. Exhaust gas converter according to claim 2,
characterized,
that the mutually adjacent contact surfaces of the individual elements (1) with source mat blanks (4) are covered. Exhaust gas converter according to claim 1 or 2,
characterized,
that the outer surface of the individual elements (1) is wrapped all around by a continuous element source mat (20). Exhaust gas converter according to one of claims 1 to 4,
characterized,
that the weight per unit area of the swelling mat material, which is preferably layered on top of one another to form the swelling mat (4, 5, 20) is greater than or equal to 1050 g / m 2 Exhaust gas converter in particular according to one of claims 1 to 5,
marked by
Protection profiles (10, 26) on the front edges - The swelling mat (5) and / or - The source mat blanks (4) and / or - The element source mat (20). Exhaust gas converter according to claim 6,
characterized, - That the protective profiles are T-shaped profile pieces (10) and - That the T-shaped profile pieces (10) with their T-base (11) in the separating joints (3) formed between the contact surfaces of two individual elements (1) are held by the adjacent source mat cuts (4) or element source mats (20). Exhaust gas converter according to claim 7,
characterized,
that the profile pieces (10) are made of sheet metal with a thickness of preferably at least 0.2 mm. Exhaust gas converter according to claim 7 or 8,
characterized,
that the clamping depth (14) of the T-base (11) is greater than or equal to 5 mm. Exhaust gas converter according to one of claims 7 to 9,
characterized,
that the total width of the two T-legs (12) projecting approximately at right angles from one end of the T-base (11) exceeds the joint width of the parting line (3) by at least 1 mm. Exhaust gas converter according to one of claims 7 to 10,
characterized,
that the T-shaped profile piece (10) is composed of two mirror-inverted rectangular profile angles (15). Exhaust gas converter according to claim 11,
characterized,
that the adjacent legs of the profile angle (15) are firmly connected. Exhaust gas converter according to one of claims 1 to 6,
marked by
a cover frame (25), preferably made of sheet steel, adapted to the line formed by the separating joints in the region of the end face of the monolith block (2), - That the frame (25) forming profile struts (26) are effective as protective profiles and cover the parting lines (3) accordingly and - That the profile struts (26) between them openings (27) leave free for the passage of the exhaust gas flow. Exhaust gas converter according to claim 13,
characterized,
that the profile struts (26) for the lateral sealing of the parting lines (3) are profiled.

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