JP2001123822A - Exhaust gas cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas cleaner for an internal combustion engine with an exhaust gas catalyst and a particulate filter device for trapping solids from an exhaust gas. SOLUTION: This cleaner is formed in an integral unit with an exhaust gas catalyst and a particulate filter device in an exhaust gas passage passing in the unit. It is desirable that the particulate filter device contain an annular filter structure arranged between a holed outer pipe and a holed inner pipe, both pipe surfaces are covered, and the exhaust gas catalyst is arranged inside an opening in one pipe surface, so that exhaust gas supplied flows through the exhaust gas catalyst into an internal cavity of the inner pipe and flows out through the holed inner pipe, the filter structure and the holed outer pipe in the substantially radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine provided with an exhaust gas catalyst and a particulate filter device for collecting solids from exhaust gas.

[0002]

2. Description of the Related Art A particulate filter known from EP 0 334 910 B1 comprises tubular filter candles, which have a filter medium on a perforated tube, the filter medium being, for example, a circular knit from ceramic thread. It is manufactured as. Such a cloth tube is attached to the tube like a sock. When the filter medium has a multilayer structure, a plurality of cloth tubes are applied to the tubes in a superposed manner.

[0003] A system for treating diesel exhaust gas, known from EP 0 418 432 B1, comprises a catalyst for oxidizing NO contained in the exhaust gas to NO ₂ , for example a ceramic honeycomb body provided with a catalyst coating. A filter device, such as a cell ceramic filter, disposed downstream of the catalyst for collecting particulates from exhaust gas.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus comprising an exhaust gas catalyst and a particulate filter which has an improved exhaust gas purifying action in a simple and compact structure.

[0005]

According to the present invention, a device according to the invention is embodied as an integrated unit having an exhaust gas catalyst and a particulate filter device in an exhaust gas passage passed through the unit. It is solved by being. Compared with a conventionally known exhaust gas purifying device including an exhaust gas catalyst in the first case and a particulate filter device in a second case at the subsequent stage, this integrated unit requires a small amount of structural space and has a very small Can be accommodated at a suitable distance. As an advantage of this, temperature loss is prevented in the exhaust gas, and regeneration of the particulate filter is facilitated.

Advantageous configurations of the device are specified in the dependent claims. In an optimal arrangement in consideration of space demand, an exhaust gas catalyst is arranged in an exhaust gas inflow passage, and a particulate filter device is arranged downstream. The particulate filter device can include an annular filter structure that substantially flows through the filter structure from a substantially axial exhaust gas inlet passage into the interior cavity of the filter structure and from the interior cavity. An exhaust gas outflow passage in the radial direction is provided, and an exhaust gas catalyst is integrated with the exhaust gas inflow passage of the particulate filter device.

In another arrangement, a particulate filter device includes an annular filter structure disposed between an outer perforated tube and an inner perforated tube, wherein both tube fronts are covered and one of the tube fronts is covered. An exhaust gas catalyst is arranged in the opening,
The supplied exhaust gas flows through this exhaust gas catalyst into the internal cavity of the inner tube, from which it is substantially radially perforated inner tube,
It exits through the filter structure and the perforated outer tube.

[0008] The filter structure desirably includes a filter cloth and a wire knit. For example, in order to achieve the optimization of the collection result by adjusting the density of the fibrous material based on the location of use of the filter structure and the exhaust gas to be purified, the filter structure may have regular or irregular alternating aids. It is possible to form a multilayer structure with a layer of a knitted wire and a fiber cloth. In order to improve the collecting action, it may be advantageous that the filter medium not only includes the fiber cloth but also has an auxiliary loose fiber material made of heat-resistant fiber.

[0009] In order to optimize the trapping effect for various applications of the filter structure, the fiber cloth has a height,
The density, weave and fiber type can be varied. The density can be different in the horizontal and vertical directions of the fiber cloth. If the weave is different, the individual warp and weft yarns can be crossed in different ways. The heat-resistant fibers can be used as ceramic fibers or glass fibers. Improved exhaust gas contact purification is achieved by the second catalyst being mounted in the inner tube at a distance from the first catalyst.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail below on the basis of an embodiment of the device according to the invention with reference to the drawings.
The exhaust gas purifying device includes a metal inner tube 4 and a metal outer tube 5, which are arranged coaxially with each other to form an annular space. The inner tube 4 is longer than the outer tube 5, and is arranged in the outer tube such that one end is flush with the outer tube and the other end projects from the outer tube 5. The front of the device with flush flush ends is tightly closed by a disk 11. On the opposite front, the annular space 2 is closed off by a ring 9. The inner tube 4 and the outer tube 5 are perforated between the disk 11 and the ring 9. The pipe portion 7 extending from the outer pipe 5 of the inner pipe 4 is
Has a closed wall.

The annular space is filled with a fiber material or a fiber cloth 3 which can be supported by a wire knit (not shown). It serves as a filter media for particulates in exhaust gases of internal combustion engines. A honeycomb body 8 with a catalyst coating is laid down in front of the outer tube 5 in the tube part 7 of the inner tube 4. The honeycomb structure of the honeycomb body 8 can be arranged directly in the tube part 7. Alternatively, it is also possible to arrange the honeycomb body 8 in another cylindrical case fitted in the tube section 7 (not shown). Honeycomb body 8
Or a cylindrical case provided optionally is welded to the inner tube 4.

The exhaust gas to be purified is supplied according to an arrow 20 via a supply unit (not shown). Since the honeycomb body and the particulate filter are arranged integrally and the inner tube 4 is a part of the particulate filter and also a support for the honeycomb body 8, a very dense device can be obtained. Exhaust gas passes therethrough flows into the catalyst 8, the CO is CO ₂ by reaction with a catalytic coating of the catalyst, HC is H ₂ O
To, and NO is (only less than about 20% of the NO present in the exhaust gas) is converted into NO _2. The exhaust gas flow supplied axially into the cylindrical interior space 12 of the inner tube 4 through the catalyst 8 is radial and / or oblique to the longitudinal axis, the perforated inner tube 4, the filter structure 1 and the outer perforated It flows uniformly outward through the tube 5. The filter structure 1 collects solid particles such as soot from diesel exhaust gas.

The embodiment shown in FIG. 2 is constructed according to the apparatus shown in FIG. 1 and has another catalyst-coated honeycomb body. This honeycomb body is pushed into the inner tube 4 while being separated from the first catalyst 8. Therefore, the other catalyst 13 is completely removed from the outer tube 5.
Inside. A portion of the exhaust gas stream flows outward through the first portion 14 of the filter structure 1 in front of the second catalyst 13 while the remaining exhaust gas stream passes through the rear portion 15 of the filter structure 1 Before, it still flows through the second catalyst 13. Additional exhaust gas contact purification takes place in the second catalyst 13. Based on the distance between the two catalysts 8, 13, the front internal space 12 in front of the second catalyst 13 and the rear internal space 1 behind it
Different pressure and flow conditions can occur within the 2 ', which allow for the adaptation and optimization of catalysis and collection. Due to the arrangement of the other catalysts 13 and the back pressure which is thereby created in the axial exhaust gas channel, the catalyst 1
Upstream before 3, the radial flow through of the filter structure 1 increases. Thus, the distribution of the radial flow component over the entire length of the filter structure 1 is improved.

[0014] In order to increase the effective surface area of the other catalyst 13, it may be desirable to provide the honeycomb body with radial holes, for example by winding a perforated plate. The radial holes further facilitate the flow of the radial exhaust gas stream into the filter structure. The other catalyst 13 is preferably welded in the inner tube 4. If that is desired, a plurality of second catalysts can be arranged in the inner tube 4 spaced apart from each other. The honeycomb structure can be configured differently to optimize the pressure conditions.

[0015]

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the device according to the invention in a schematic longitudinal section.

FIG. 2 shows a second embodiment of the device according to the invention in a schematic longitudinal section.

[Explanation of symbols]

 1 particulate filter device 8 exhaust gas catalyst

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) (71) Applicant 500315714 Amselstrasse 4, 82467 Garmisch-Partenkirchen, Germany (72) Inventor Mangold Macchiaz Eschenloch, Germany 82438 Schelemberstrasse 1

Claims (6)

[Claims] In an exhaust gas purifying apparatus for an internal combustion engine, comprising an exhaust gas catalyst and a particulate filter device for collecting solids from the exhaust gas, the device comprises an exhaust gas catalyst (8) in an exhaust gas passage passed through the unit. And a particulate filter device (1) formed as an integral unit. 2. An exhaust gas catalyst (8) in an exhaust gas inflow passage,
And downstream of the particulate filter device (1)
2. The device according to claim 1, wherein is arranged. 3. The particulate filter device (1) has an annular filter structure (1, 4, 5), which filter structure is inside an internal cavity (12) of the filter structure (1, 4, 5). A substantially axial exhaust gas inflow path to the filter and a substantially radial exhaust gas outflow path from the internal cavity (12) through the filter structure (1, 4, 5). (1) an exhaust gas catalyst (8) is integrated with the exhaust gas inflow passage,
An apparatus according to claim 1. 4. A particulate filter device (1)
Comprises an annular filter structure (1, 4, 5) arranged between the outer perforated tube (5) and the inner perforated tube (4), both tube fronts (6, 10) being covered. , One tube front (6)
An exhaust gas catalyst (8) is arranged in the opening of the inner pipe (4), through which the supplied exhaust gas flows into the inner cavity (12) of the inner pipe (4), from which it is substantially radially perforated. And (4) flowing out through the filter structure (1) and the perforated outer tube (5).
The device according to any one of claims 3 to 7. 5. The filter structure according to claim 1, wherein the filter structure comprises a filter cloth and a wire knit.
The device according to any one of claims 4 to 7. 6. A method according to claim 1, wherein the second catalyst is mounted in the inner tube at a distance from the first catalyst. The described device.