AU764496B2

AU764496B2 - Device for treating exhaust gas

Info

Publication number: AU764496B2
Application number: AU64256/00A
Authority: AU
Inventors: Alfred Ernst Buck
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-06-29
Filing date: 2000-06-29
Publication date: 2003-08-21
Anticipated expiration: 2020-06-29
Also published as: AU6425600A; DE50010050D1; DE19929911C2; CA2377027A1; ATE293209T1; EP1192336B1; WO2001002705A1; EP1192336A1; JP2003505629A; DE19929911A1

Abstract

A device (1) for treating exhaust gas from internal combustion engines, comprising a housing (2) containing an insert (5) which is comprised of two types of knitted hoses (13,14). One knitted hose (13) exclusively consists of metal wire while the other knitted hose (14) consists of either mineral fibers alone or mainly consists of mineral fibers. The knitted hose (13) produced from metal wire forms meshes which protrude from the knitted mineral fiber hose (13) on the intake side in order to receive additional heat and conduct it towards the inside of the insert (5). It is possible to arrange the insert (5) at a sufficient distance from the exhaust of the engine, whereby overheating in the full load range can be prevented and reaction of the catalytic material on said insert can also be guaranteed in the partial load range of the internal combustion engine.

Description

WO 01/02705 PCT/DE00/02037 Device for treating exhaust gas A catalytic converter for the exhaust gas stream of an internal combustion engine is described in DE-C-43 03 850. The catalytic converter consists of a mineral-fibre knitted fabric which is arranged in layers either by being folded in a zigzag formation or coiled up. The through-flow of the body thus obtained occurs in a direction parallel to the individual layers. The fibres, from which the knitted fabric is produced, are coated with a suitable catalyst material, for example platinum.

The big advantage of this arrangement consists in a highly effective cleaning of the exhaust gas WO 01/02705 PCT/DE00/02037 stream, while on the other hand there is no risk of destroying the inherently flexible knitted fabric. In addition, since the knitted fabric is manufactured as a tubular fabric, there are no free edges at which the knitted fabric can start to unravel. Even if broken threads should appear within the body formed by the knitted fabric, the fabric nevertheless remains sound in its structure because, on account of the mesh, the broken thread is held on both sides of the break.

Another form of design of catalytic converters are the so-called monoliths, in which a porous, gas-permeable ceramic body is coated with the catalyst material. These ceramic bodies have the disadvantage of possibly shattering in the exhaust gas stream.

Regardless of the way in which the base for catalyst material is formed, the known catalytic converters display problems with the reaction in the partial load range and with low power settings of the internal combustion engine. The reason for this being that the exhaust gas stream has too small a volume at these lower engine powers, and is not capable of bringing the catalytic converter up to the process tempelature at wIhlich thue caatalyst mllatial is cpblev .f dissociating the nitrogen oxide. The low-volume exhaust gas stream is excessively cooled in the exhaust pipe.

In order to be able to get the catalysis operating properly at low engine powers, the catalytic converter has to be brought closer to the exhaust outlets of the internal combustion engine so that there is not excessive cooling in the exhaust pipe. However, this results in the catalytic converter being thermally destroyed at high engine powers. The large volume exhaust gas stream is not cooled so greatly. With a short distance between the exhaust outlet of the cylinder and catalytic converter in combination, as is required for the partial load range, the -2exhaust gas stream with the large mass flow would heat up the catalytic converter to a relatively high temperature, which would be raised even further as a consequence of the catalytic disintegration of the NO,. Because of that, temperatures inside the catalytic converter are attained which thermally destroy or least damage the catalyst material.

In principle similar conditions are met with self-regenerating soot filters. Too large a distance between the soot filter and the exhaust outlet of the cylinder leads to temperatures which are too low in the partial load range of the engine. Higher temperatures would be necessary so that the soot is burnt catalytically in the filter. Too small a distance between the soot filter and the exhaust outlet results in temperatures which are too high at high engine powers.

Starting from this, it would be desirable to create a device for treating exhaust gas from internal combustion engines, which operates reliably both in the lower power range and the partial load range of the internal combustion engine without the risk of it being thermally destroyed with the engine at full load.

Object of the Invention It is an object of the present invention to substantially overcome or at least 20 ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful .alternative.

""Summary of the Invention The invention provides a device for treating exhaust gases from internal combustion engines, comprising a casing which has an exhaust gas inlet and an exhaust gas outlet, with at least one casing insert which, with regard to the flow, is arranged i :between the exhaust gas inlet and the exhaust gas outlet, whereby the casing insert has an inlet side facing the exhaust gas inlet and an exhaust side facing the exhaust gas outlet, 30 the casing insert has at least one first layer of a textile fabric, which extends between the inlet side and the exhaust side, and the casing insert has at least one second layer of a textile fabric, which extends between the inlet side and the exhaust side, which textile fabric container metal wire and protrudes at least beyond the first layer on the inlet side in such a way that the exhaust gas stream flows essentially parallel to the layers through the casing insert.

-3- [R:\LIBD]03537.doc:caa With the device according to the preferred embodiment, textile fabrics which are stacked in layers, are again used as the base material for the catalyst material. The structure thus formed is assembled from two different types of layers, namely layers which consists exclusively of wire, and layers which are formed either of only mineral fibres or a combination of wire and mineral fibres. The layers consisting exclusively of wire are arranged so that on the inlet side they protrude a short way, for example 3 to 10 mm, beyond the other layers.

0* -3a- *o 3a [R:\LIBD]03537.doc:caa WO 01/02705 PCT/DE00/02037 In comparison with mineral fibres, wire is a relatively very good heat conductor, and based on that, the protruding wire layers warm up very rapidly in the exhaust gas stream and conduct the high temperatures into the interior, or that is to say among the layers of mineral fibres. In this way, the catalysis is set into operation and accordingly continues to heat up the catalytic converter. The new catalytic converter therefore can be placed at a distance from the exhaust outlet of the cylinder, the distance being so great that there is no risk of overheating the catalytic converter even at full load operation of the engine.

In principle, similar conditions again exist in a self-regenerating soot filter, in which the soot deposited on the wire or fibres can burn off with or without a catalytic coating and in fact even when the vehicle is operating only in the partial load range.

A casing insert, which is very resistant to mechanical damage due to the exhaust gas stream, is obtained if at least the first and/or second layer consist(s) of a mesh product. The expert understands "mesh product" to mean a knitted fabric The mesh product is in turn extremely robust if it is manufactured as tubular fabric or tape WIL'h SIr1eIg.te ege, because Lonth one hand a double-layered formed body is produced directly and in addition on the sides there are no free edges where there is risk that the knitted fabric could start to unravel. The tubular fabric is continuous in the circumferential direction, with which there are no stitch wales that would not be bound between adjoining wales.

Advantageously the first layers are joined to one another, one below the other, in one piece, as also is the case for the second layer. To achieve this, the starting material for the first layer and for the second layer is laid one layer on top of the other. The double-layered formed body thus obtained is either in folded in zigzag formation or coiled up. The first and second layers then -4- WO 01/02705 PCT/DE00/02037 each alternate in the stack.

Depending on the type of internal combustion engine in which the device is to be used, the catalyst material is a catalyst material for nitrogen oxide or a catalyst material for the oxidation of soot. Finally the new device can also be used as a self-regenerating filtering device for fine particles, such as occur both in the diesel and spark ignition engines.

Moreover, improvements are the subject matter of sub-claims. Implementation examples of the subject matter of the invention are represented in the drawing, which shows: in Fig. 1, the device according to the invention in a schematic longitudinal section, in Fig. 2, the insert according to Fig. 1 in a perspective schematic representation, and in Fig. 3, a further form of implementation for the insert of the device according to Fig. 1, likewise in a perspective cut-out representation.

Fig. 1 shows a schematic form of a device 1 for treating the exhaust gas of an internal combustion engine, for example a diesel or spark ignition engine.

The device 1 has a casing 2 which is provided with an intake fitting 3 and exhaust fitting 4.

The intake fitting 3 is designed for example to connect to the exhaust gas manifold of the internal combustion engine, while the exhaust pipe is connected to 4.

An insert 5 is located inside the casing 2. As shown the insert 5 completely fills the profile section of the interior of the casing 2. The insert 5 is secured to the side which faces the inlet fitting 3 by means of a circular fastening strap 6 which is attached to the casing 2. A boss 7 is fixed in the casing 2 at a distance from the circular fastening strap 6: The boss .serves as the bearing surface for the insert 5 and is to prevent the exhaust gas stream from moving the insert in the direction of the exhaust fitting 4.

The boss 7 contains a plurality of holes 8 and can also be formed by a close meshed sieve which is welded onto the inner face of the casing 2.

The through flow of the device I takes place from the inlet fitting 3 to the exhaust fitting 4 in the direction of the arrow 9. Consequently an inlet side 11 and an exhaust side 12 is formed in the insert The construction of the insert 5 is given in Fig. 2.

The insert 5 consists of two drum-like, coiled up, knitted tubes 13 and 14. The knitted fabric tube 13 consists of metal wire 15 which is knitted up by forming a mesh 16. This produces a formed body which is continuous in the circumferential direction and in which the stitch wales 17 formed by the knit run in the direction of the jacket line of the knitted tube. The stitch rows S lie in the circumferential direction.

The second knitted fabric tube 14 likewise consists of a mesh 18, in which the fibres, from .oo.

which the knitted fabric tube 18 is manufactured, are mineral fibres. Depending on the aim of application, these mineral fibres are coated with a catalyst material for soot or a catalyst material for NO, In addition, in the case of glass fibres, these are leached if necessary.

-6- WO 01/02705 PCT/DEOO/02037 The fabric tubes produced 13, 14 are laid flat, as can be seen in Fig. 2 and coiled up together over the short end. This results in the drum-like formed body shown in Fig. 2. The width of the knitted fabric tube 13 in proportion to the width of the knitted fabric tube 14 is chosen so that when both knitted fabric tubes 13, 14 are pressed flat, the breadth of the knitted fabric tube 13 made of metal wire 15 is slightly greater than the breadth of the knitted fabric tube 14 made of mineral fibres. Because of this, on one of the sides of the insert 5 the knitted fabric tube 13 protrudes beyond the edge of the knitted fabric tube 14.

Production of the insert 5 occurs as follows: The knitted fabric tube 13 is knitted from metal wire 15 on suitable circular knitting machines.

Likewise the knitted fabric tube 14 is produced from mineral fibre threads on a circular knitting machine. Then the knitted fabric tube 14 made of mineral fibres is laid on the knitted fabric tube 13 made of metal wire and is laid on in such a way that the laid-flat knitted fabric tube 14 coincides at one edge flush with the correspondiig edge of the lid, fiat knitted fabric tube 13 made of metal wire.

Due to its different width, the metal wire knitted fabric tube 13 protrudes at the other edge beyond the edge of the knitted fabric tube 14, as can be seen schematically in Fig. 2. Then the double-ply formed body made from the two flat-lying knitted fabric tubes 13 and 14 is coiled up over the short end, as is also shown in Fig. 2. Coiling up is continued until a coil is formed with a diameter which is equal to the inside diameter of the casing 2. Then the coil produced is cut off from the stock of knitted fabric tubes 13 and 14. The coil now obtained constitutes the insert 5, which is arranged in the casing 2. It is placed in the casing 2 in such a way that the -7- WO 01/02705 PCT/DE00/02037 coil face, at which the metal wire knitted fabric tube 13 protrudes, is facing the intake fitting 3, i.e. it forms the inlet side 11 of the insert As follows from the explanation of the manufacturing process, referring to the radial direction of the insert 5, a first layer formed by the knitted fabric tube 14 alternates each time with a second layer, formed from the knitted fabric tube 13 made of metal wire. Because of the arrangement of the coil, or that is to say the insert 5, the through-flow of the insert 5 occurs essentially in a direction parallel to the approximately cylindrical surfaces (put more precisely, spiral-shaped surfaces), which are defined by the layers of the flattened knitted fabric tubes 13, 14. With reference to the principal direction, namely the communication between the intake fitting 3 and the exhaust fitting 4, the through-flow occurs approximately in a direction parallel to the stitch rows 17, only the macroscopic through-flow being considered with this definition of the direction of through-flow. Viewed microscopically, a stream filament certainly can lead through a layer because of turbulence.

Since the metal wire knitted I'abric tube 13 protudes beyond the knitted fabric tube -14 on the inlet side 11, the formed body is very much more open-worked in this area. In addition, the metal wire has better heat-conducting properties than mineral fibres. On the inlet side, the metal wire can absorb heat much more quickly, and conducts this heat among the mineral fibre layers, namely the layers which are formed by the knitted fabric tube 14. Through this it is also possible to bring the insert 5 up to temperatures in the partial load range of the engine, at which temperatures it can fulfil its catalytic function at a spatial interval from the exhaust outlet, which prevents thermal destruction of the insert The catalytic action can be further enhanced, if necessary, if additionally the metal wire of the -8- WO 01/02705 PCT/DE00/02037 knitted fabric tube 13 also is coated with a catalyst material.

Instead of producing a cylindrical coil, as shown in Fig. 2, it is also possible to produce a coil, which in the top view has the shape of an oval, so that the extent of the casing 2 adapted to that shape is of different size in two mutually perpendicular directions. A configuration of this type has advantages, for example if the arrangement has to be housed beneath a vehicle's floor.

In the previously explained example of implementation, in each case the two knitted fabric tubes 13, 14 are coiled up, i.e. they more or less follow a spiral.

Fig. 3 shows one form of implementation in which the two knitted fabric tubes 13, 14 are zigzag folded into a stack. As a consequence of the folds being arranged in a zigzag formation, each two layers formed by the knitted fabric tube 14 lie directly on top of each other, which, when viewed in the direction of the stack, results in two layers of the knitted fabric tube 13 lying directly on top of each other. Also with this type of configuration of the insert 5, the same action can be obtained as with the arrangement accorning to ig. 2.

A device for treating exhaust gases from internal combustion engines has a casing 2 in which is located an insert 5 which is composed of two types of knitted fabric tubes 13, 14. One knitted fabric tube 13 consists exclusively of metal wire, while the other knitted fabric tube 14 consists either of only mineral fibre or predominantly mineral fibre. The knitted fabric tube 13 produced from metal wire forms a mesh which protrudes beyond the mineral fibre knitted fabric tube 13 on the inlet side, in order to additionally absorb heat and to transmit it into the inside of the insert 5. Through this, it is possible to arrange the insert 5 at such a distance from the exhaust of the engine that overheating in the full load range is avoided, while on the other hand the -9- WO 01/02705 PCT/DE00/02037 response of the catalyst material on the insert is guaranteed as well in the partial load range of the internal combustion engine.

Claims

1. A device for treating exhaust gases from internal combustion engines, comprising a casing which has an exhaust gas inlet and an exhaust gas outlet, with at least one casing insert which, with regard to the flow, is arranged between the exhaust gas inlet and the exhaust gas outlet, whereby the casing insert has an inlet side facing the exhaust gas inlet and an exhaust side facing the exhaust gas outlet, the casing insert has at least one first layer of a textile fabric, which extends between the inlet side and the exhaust side, and the casing insert has at least one second layer of a textile fabric, which extends between the inlet side and the exhaust side, which textile fabric contains metal wire and protrudes at least beyond the first layer on the inlet side in such a way that the exhaust gas stream flows essentially parallel to the layers through the casing insert.

2. A device according to claim 1, wherein the casing insert has several first layers and several second layers and at least one first layer is located between two neighbouring second layers.

3. A device according to claim 1, wherein the first and/or second layer 20 consists of a mesh product. A device according to claim 1, wherein the first and/or second layer consists of a mesh tubular fabric laid-flat or knitted fabric tape, in which the stitch wales lie in the tube longitudinal direction, or that is to say the tape longitudinal direction. A device according to claim 2, wherein at least the main part of the first layers, preferably all of the first layers, are joined together as one piece. S' 6. A device according to claim 2, wherein at least the main part of the 30 second layers, preferably all of the second layers, are joined together as one piece. A device according to claim 2, wherein the first and second layers are S"formed by zigzag folding of the starting products which form the respective textile fabrics. -11- [RLIBD]03537.doc:caa

8. A device according to claim 2, wherein the first and second layers are formed by rolling up jointly the starting products which form the respective textile fabrics.

9. A device according to claim 3, wherein the stitch wales run at right angles to a connecting line between the exhaust gas inlet and the exhaust gas outlet. A device according to claim 1, wherein the material for the first layer is exclusively mineral fibres.

11. A device according to claim 1, wherein the material for the first layer is mineral fibres and metal wire.

12. A device according to claim 11, wherein at least the mineral fibres are coated with a catalyst material.

13. A device according to claim 1, wherein the material for the second layer is exclusively metal wire. oooo oooo oO o o o, go g o oo o o ,oo oooo

14. catalyst material. A device according to claim 13, wherein the metal wire is coated with a

15. A device according to either one of claims 12 and 14, wherein the catalyst material is used as a catalyst for soot.

16. A device according to either one of claims 12 and 14, wherein the catalyst material is used as a catalyst for NO.

17. A device according to claim 1, wherein the casing insert functions as a 30 soot filter.

18. A device according to claim 1, wherein the casing insert functions as a nitrogen oxide catalyst.

19. A device according to claim 1, wherein the casing insert functions as a fine particle filter. -12- [R:\LIBD]03537.doc:caa A device for treating exhaust gases from internal combustion engines, said device being substantially as hereinbefore described with reference to the accompanying drawings. Dated 25 June, 2003 Alfred Ernst Buck Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON a o a** [R:\LIBD]03537.doc:caa