KR101001349B1 - Housing arranged in an exhaust gas system for a combustion engine - Google Patents

Abstract

The container arrangement is for incorporation in the exhaust gas system of an internal combustion engine and comprises an outer casing (1) enclosed by a tubular body (4) and a passage for conducting exhaust gases through the container. The passage has a first part extent (17a) located externally around the tubular body, a second part extent (17b) located inside the tubular body and a third part extent (17c) which handles the flow of exhaust gases between the first and second part extents. The third part extent incorporates at least one flow path, which constitutes an extended flow extent for exhaust gases in relation to a straight-line radial flow between the first and second part extents.

Description

HOUSING ARRANGED IN AN EXHAUST GAS SYSTEM FOR A COMBUSTION ENGINE}

The present invention relates to a converter device to be installed in an exhaust gas system of a combustion engine.

In recent years, more and more stringent requirements are being introduced, at least in Europe, with respect to emissions from diesel powered vehicles. Increasingly stringent requirements for efficient exhaust gas cleaning are also being set for other types of combustion engines besides diesel engines. In order to meet these emission requirements, the exhaust system of a vehicle driven by a combustion engine is equipped with a catalyst which reduces the amount of nitrogen oxides in particular in the exhaust gas and a particle filter which reduces the amount of soot particles. The components of this exhaust gas cleaning mainly act like a low-pass filter. In other words, the low frequency sound, the dominant element of exhaust noise, passes through the components of the exhaust gas cleaning with little attenuation. Accordingly, additional noise attenuation volumes need to be added to the exhaust system to compensate for the volume occupied by the particle filter and catalyst device in the exhaust system. Therefore, such converter devices are relatively long and therefore occupy considerable space in the vehicle.

It is an object of the present invention to provide a converter device which is advantageous in terms of space occupied while at the same time having good acoustic attenuation characteristics, especially for low frequency noise in the exhaust system of a combustion engine, and which is flexible and easy to maintain.

The above object is achieved by an apparatus characterized by the matter described in the characterizing part of claim 1.

Good attenuation of low frequency engine noise in combustion engines typically requires an elongate passage that leads the exhaust gas through the converter device. Since the passageway according to the invention comprises a first part outside the periphery of the tubular body and a second part inside the tubular body, there is substantially a two-way flow of exhaust gas within the converter device. . This two-way flow provides a fairly long passage for the exhaust gas passing through the converter device, thereby automatically providing good acoustic attenuation of low frequency noise. Properly forming passage shapes provide two-way flow in the converter device with relatively little flow resistance. If a properly shaped passageway is provided, the flow resistance may not be much larger than with a conventional converter having a substantially straight passageway for exhaust gases. By introducing a flow path that provides a longer distance of flow to the exhaust gas than a substantially straight radial flow between the first outer portion and the second inner portion, there is no need to increase the length of the converter device. Extend the passage further. As such, the converter device according to the invention provides a long passage for the exhaust gas in a short and compact structure which achieves a very good attenuation of low frequency engine noise.

According to a preferred embodiment of the invention, the flow path is positioned to connect the first space and the second space of the passage. The basic principle for attenuating low frequency noise is to create a long exhaust line between two relatively large spaces. It takes up a large space between the two large spaces for the exhaust gas because it requires a considerable length to achieve effective low frequency noise attenuation by a conventional straight flow path. Proper positioning of the flow path between two large spaces in the converter device results in a converter device having a short and compact structure and at the same time exhibiting good acoustic attenuation characteristics.

According to another preferred embodiment of the present invention, the flow path has a spiral extent. These spiral flow passages have a relatively large outer diameter, with the result that the flow passage is considerably longer than the substantially straight radial flow route between the first portion located outside the pipe and the second portion disposed inside the pipe. . The spiral flow path can be made very compact and the main extension range is in the radial plane. This spiral passage allows the converter device to be made very short and compact despite the fact that it constitutes a considerable length of passage for the exhaust gas. The spiral flow path also provides adequate control of the exhaust flow, which is substantially optimal. The flow loss in the flow path can be kept lower to a low level.

According to another preferred embodiment of the invention, the flow path exhibits a spiral extension range of 180 ° to 1080 °. Spiral flow paths, for example, may extend over a significant length of just one revolution, providing good acoustic attenuation. The flow path may have at least one portion whose cross-sectional area changes. The cross-sectional area of the flow path can be varied to control the attenuation of exhaust noise and flow resistance. The cross-sectional area may include, for example, a cross-sectional area that increases in the flow direction of the exhaust gas. The velocity of the exhaust gas is reduced by the increasing cross-sectional area in the flow direction. Accordingly, the resistance of the flow through the flow path will be lower.

According to another preferred embodiment of the invention, the flow path comprises at least one profiled section having a helical extension range. This contour portion may be elongated and exhibit a length corresponding to the length of the flow path. The contour forming portion forms the wall surface of the flow path. The third portion includes n flow paths formed by n contouring portions spaced apart from each other by 360 ° / n. In order to make the flow of the exhaust gas easier, at least two flow paths are preferably used. The two flow paths have respective inlets and outlets 180 ° apart from each other. The result is a substantially uniform distribution of exhaust gas between the two flow paths. In order to further promote a uniform distribution of exhaust gas between the flow paths, the number of flow paths can be further increased. Three or more flow paths preferably have inlets and outlets away from each other in accordance with the above formula in order to distribute the exhaust gas evenly among the several flow paths. Also, the length of the third portion can be increased in this way.

According to another preferred embodiment of the invention, the exhaust gas is directed through the passage in a direction in which it first flows through the first portion located radially outward of the pipe before flowing through the second portion located inside the pipe. It is done. This direction of flow of exhaust gas through the passage has many advantages. In particular, it has the advantage of facilitating the assembly of the components of the converter device, facilitating the design of the flow path so that an effective acoustic attenuation can be achieved, and simplifying the installation of the burners if necessary at the passage entrance. The burner is for raising the temperature of the exhaust gas, if necessary, before the exhaust gas reaches the particle filter. In order for the soot particles in the exhaust gas to ignite and burn in the particle filter, the exhaust gas needs to reach a certain temperature.

According to another preferred embodiment of the present invention, the flow path includes a detachable module. The module makes it possible to assemble and disassemble the flow path to the converter device. Such modules can be manufactured in various shapes and sizes. Accordingly, the modules comprise different lengths and different numbers of flow paths, which are suitable for combustion engines of different types and sizes. The detachable module includes one end wall of the casing. The module forms a side cover that is very substantially easy to insert and remove.

1 is a view showing a converter device according to the present invention.

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a cross-sectional view taken along line B-B of FIG. 1.

4 is a cross-sectional view taken along line C-C of FIG. 1.

5 is a diagram illustrating only one module including a spiral flow path.

Preferred embodiments of the invention are described below by way of example with reference to the accompanying drawings.

1 shows a converter device arranged in an exhaust system for a diesel powered vehicle. The converter device comprises an outer casing 1 having a substantially cylindrical shape. In FIG. 1, the casing 1 site facing the observer has been removed to show the components arranged inside the casing 1. The casing 1 forms a closed outer surface except at the point where the inlet part 2 and the outlet part 3 for the exhaust gas are arranged. The pipe 4 of circular cross section is arranged inside the casing 1 such that the casing 1 and the centerlines passing through the pipe 4 coincide. The length of the pipe 4 extends from the first end wall 5 of the casing 1 to the module M comprising the second end wall 6 of the casing 1.

The converter device comprises an exhaust cleaning component for cleaning the exhaust gas flowing through a flow path extending between the inlet 2 and the outlet 3. A first exhaust cleaning component in the form of a particle filter 7 is installed externally around the pipe 4. FIG. 2 shows a cross section along line A-A of FIG. 1 and shows a particle filter 7 extending annularly around the pipe 4. The particle filter 7 has a radial extension range that completely fills the radial space between the pipe 4 and the casing 1. The particle filter 7 comprises elongated ducts having an extension range in the first direction 8. The long duct is for directing the exhaust gas through the particle filter 7. The particle filter 7 has a constant cross-sectional shape in the flow direction of the exhaust gas. Therefore, the exhaust gas is led in the first direction 8 substantially through the particle filter 7. The particle filter 7 comprises stop surfaces 9 installed at appropriate points along the elongation range of the long duct. By the stop face the exhaust gas is led from the stop face 9 into an adjacent elongated duct in the particle filter. At this time, soot particles are collected and burned in the particle filter 7. A second exhaust cleaning component in the form of a catalyst cleaner 10 is arranged inside the pipe 4. The catalyst cleaner 10 is arranged radially within the particle filter 7 range. The catalyst cleaner 10 includes elongated ducts for directing exhaust gas through the catalyst cleaner 10 in a substantially second direction 11. The catalyst cleaner 10 has a constant cross-sectional shape in the exhaust gas flow direction 11. The catalyst cleaner 10 is for achieving catalytic cleaning of the exhaust gas, and particularly for reducing nitrogen oxides in the exhaust gas passing through. The particle filter 7 has a larger cross-sectional area than the catalyst cleaner 10 in the plane A shown in FIG. 2. The flow resistance of the exhaust gas is related to the flow rate. Because of the stop surfaces 9, the flow resistance of the exhaust gas is generally greater in the particle filter 7 than in the catalyst cleaner 10. Lowering the flow rate through the particle filter 7 can significantly reduce the overall flow resistance through the flow path. The cross-sectional area of the particle filter 7 is preferably about twice the cross-sectional area of the catalyst cleaner 10.

The basic principle of attenuating low frequency noise is to create a long exhaust path between the two spaces. If the exhaust path is straight, an effective low frequency noise attenuator takes up considerable space. Low frequency sound is the dominant factor in the noise of combustion engines. The converter device comprises sound attenuating means designed according to the above basic principle. At this time, the converter device comprises two profiled sections 12a, 12b extending helically. In this case, each of the contour forming portions 12a, 12b extends 1.5 revolutions, that is, 540 °. The two contouring portions 12a and 12b form wall surfaces for the two helical flow passages 13a and 13b whose inlet and outlet portions are 180 degrees apart from each other. The spiral flow passages 13a and 13b are disposed inside the module M. As shown in FIG. The exhaust gas is located inside the pipe 4 from the first portion 17a of the passage located outside the pipe 4 via the third portion 17c of the passage including the spiral flow passages 13a and 13b. It is directed radially to the second portion 17b of the passage. The space in the passage outside the pipe 4 upstream of the flow passages 13a and 13b constitutes the first space, and the space inside the pipe downstream of the flow passages 13a and 13b constitutes the second space. Inducing exhaust gas into the flow passages 13a and 13b having a radially extending range enables the converter device to achieve a long exhaust path without having to have a long shape. Therefore, a converter device comprising both an exhaust cleaning component and an acoustic damping component can be made quite compact and take up little space while exhibiting very good acoustic damping characteristics.

If necessary, a burner 14 may be installed near the inlet 2 of the converter device. The burner 14 is for heating the exhaust gas to a temperature at which soot particles can burn in the particle filter 7. The soot particles are usually ignited at a temperature of around 600 ° C., but in most cases it is difficult to ensure such a high exhaust temperature even with the high performance burner 14. Therefore, the ignition temperature of the soot particles should typically be lowered. This is achieved by converting the various types of nitrogen oxides NO _{x generated} into nitrogen dioxide NO ₂ . There are basically two ways to achieve this. According to the first method, CRT (Continuous Regeneration Trap), an independent oxidation catalyst cleaner is disposed in front of the particle filter 7 in the exhaust gas flow direction. In such a state, the soot particles ignite at about 225 ° C in the particle filter 7. According to the second method, CSF (Catalytic Soot Filter), the particle filter 7 is suitably coated so that oxidation catalysis from NO _x to nitrogen dioxide NO ₂ occurs directly on the surface of the particle filter 7. It is coated with a lining material. In this case, the soot particles are ignited at about 250 ° C. It is also possible to add various additives to the fuel to achieve lower ignition temperatures on the order of 350 ° C. in conventional particle filters 7.

When a catalytic filter 10 acting by SCR (Selective Catalytic Reduction) is used, an injection device 15 is arranged at the circumference of the converter 1, for example in the form of an ammonia carrier (ammonia carrier) material is added. When an ammonia carrier is added, in order to optimize the performance of the catalytic filter 10 in decomposing ammonia and nitrogen oxides in the exhaust gas passing through with nitrogen gas and water, the ammonia carrier needs to be mixed properly. Such mixing is not a problem when the long spiral flow passages 13a and 13b are provided.

The exhaust gas flows into the converter device through the inlet portion 2. 3 shows a B-B cross section through the converter device at the inlet 2. Exhaust gas is led from the inlet 2 to the first portion 17a of the passageway, which represents a substantially annular space extending outward around the pipe 4. The annular space of the first portion 17a of the passage gives relatively little flow resistance to the incoming exhaust gas and is substantially reduced before the exhaust gas is directed to the particle filter 7 in the axial direction outside the pipe 4. Produces a uniform exhaust gas distribution. Before the exhaust gas reaches the particle filter 7, the exhaust gas is heated by the burner 14 to a temperature sufficient to ensure ignition and combustion of the soot particles in the exhaust gas in the particle filter 7. . The exhaust gas is directed in the first direction 8 through the elongated ducts of the particle filter 7. A stop surface 9 disposed at an appropriate point along the elongated ducts in the particle filter 7 forces the exhaust gas into the adjacent elongated ducts. Depending on the soot removal system and the temperature, soot particles collected in the particle filter 7 are ignited and combusted at this stage. The exhaust gas is forced to deflect sideways such a short distance, but the exhaust gas mainly flows in the first direction 8 along a substantially straight line passing through the particle filter 7. The exhaust gas exiting the particle filter 7 is in principle removed with soot particles.

The exhaust gas exiting the particle filter 7 has a substance in which an ammonia carrier is added to the exhaust gas by the injection device 15 before reaching the module M. Module M is shown separately in FIG. 5. The module M comprises a wall surface 18 which abuts against the pipe 4 in the radially inner region. The wall surface 18 includes a first inlet portion 19a for guiding the exhaust gas into the first flow passage 13a and a second inlet portion 19b for guiding the exhaust gas into the second flow passage 13b. Spiral contoured portions 12a, 12b, which can be partially identified in the figure, form first and second flow paths 13a, 13b. The module unit M also comprises a second end wall 6 of the casing 1 and an outer radial area 20. The module unit M is detachably fitted to the other parts of the converter device in a suitable manner, for example by clamping. The exhaust gas is led radially in the module M via one of the two flow paths 13a, 13b formed by the spiral contouring portions 12a, 12b. The inlets 19a and 19b of the two flow passages 13a and 13b are 180 degrees apart from each other, so that the exhaust gas is substantially uniformly distributed between the two flow passages 13a and 13b. The exhaust gas subsequently introduced radially via the helical flow passages 13a and 13b of the third portion 17c of the passageway is provided with the first portion 17a of the passageway located outside the pipe 4 and the pipe 4. Between the second portions 17b of the passage located therein, there is a considerably longer transport path than the substantially straight radial flow. The helical flow passages 13a and 13b form a long exhaust path connecting the two spaces of the passage so that an effective acoustic attenuation of the low frequency noise of the diesel engine is achieved. The long helical flow paths 13a and 13b also provide the necessary mixing distances for the ammonia carrier, allowing the ammonia carrier to be distributed substantially uniformly in the exhaust gas. As the exhaust gas passes through the helical flow passages 13a and 13b, the flow direction undergoes a relatively small change, thereby decreasing the flow resistance. The spiral flow paths 13a and 13b result in flow in a plane substantially perpendicular to the first flow direction 8 and the second flow direction 11 of the exhaust gas. The exhaust gas exiting the helical flow path is led into the pipe 4. The exhaust gas which escaped from the flow paths 13a and 13b is accommodated in the space 21 located in the center of the module M before being led to the pipe 4 and directed to the catalyst cleaner 10. When the exhaust gas flowing inside the pipe 4 reaches the catalyst cleaner 10, the exhaust gas flows into the long ducts of the catalyst cleaner 10. The elongated ducts allow the exhaust gas to flow in a second flow direction 11 parallel to, but parallel to, the first flow direction 8. In the catalyst cleaner 10, the nitrogen oxides and ammonia contained in the exhaust gas are decomposed into nitrogen gas and water. Then, the exhaust gas from which the soot particles and nitrogen oxides have been substantially removed exits through the outlet portion 3. The outlet part 3 comprises a smoothly curved inclined shape which connects the pipe 4 to a narrower pipe of the exhaust system. Narrower 5 is not shown in the figure. The shape of the outlet 3 causes the exhaust gas to here also receive little flow resistance here.

As such, the flow paths 13a and 13b are contained within a detachable, independent module M that is easy to insert and remove. This means that the end wall 6 and the flow paths 13a and 13b can be fitted into one unit. Such a module M may be manufactured in various shapes and sizes. Modules M, including flow paths with different numbers, lengths and cross sections, can be mounted to the converter device, in particular depending on the type and size of the combustion engine. The fitting of the module can be done by clamping.

The invention is in no way limited to the embodiments described but may be varied freely within the scope of the claims. For example, the flow path need not necessarily be a helical extension range and may have a curve extension range of substantially any desired shape such that it is a longer exhaust gas path than a substantially straight radial flow. The direction of the exhaust gas may be reversed so that the exhaust gas first flows inside the pipe 4 and then becomes the final flow outside the pipe 4 radially outward via the flow paths 13a and 13b. . In this case, the particle filter 7 is arranged inside the pipe 4 and the catalyst cleaner 10 is arranged outside the pipe 4. The cross section of the casing 1, the exhaust cleaning components 7, 10 and the pipe 4 need not necessarily be circular and may be substantially any desired functional shape. In addition, the pipe 4 need not be disposed inside the casing 1 but can be disposed at substantially any desired functional position.

Claims (11)

A converter device installed in an exhaust system of a combustion engine, An outer casing 1, a tubular body 4 surrounded by the casing 1, and a passage for guiding exhaust gas through the converter device, The passage includes a first portion 17a located outside the tubular body 4, a second portion 17b located inside the tubular body 4, the first portion 17a and the second portion. A third portion 17c providing a flow of exhaust gas in the radial direction between the 17b, The third portion provides the exhaust gas with a flow path longer than the substantially straight radial flow between the first portion 17a located outside of the passageway and the second portion 17b located therein. In the converter device provided in the exhaust system of a combustion engine containing at least one flow path 13a, 13b, The flow paths 13a and 13b are Has a spiral extent of 180 ° to 1080 °, Including at least one profiled section 12a, 12b that forms the wall surface of the flow path 13a, 13b and has a helical extension range. A converter device installed in an exhaust system of a combustion engine. 2. A converter device as set forth in claim 1, wherein said flow paths (13a, 13b) are positioned to connect the first space and the second space of the passage. delete delete 3. Converter device according to claim 1 or 2, characterized in that the flow passage (13a, 13b) has at least one part of which the cross-sectional area is varied. delete 3. The passage (3) according to claim 1 or 2, wherein the third portion (17a) of the passageway comprises n flow paths (13a, 13b) formed by n contour forming portions (12a, 12b) spaced 360 ° / n from each other. And a converter device installed in an exhaust system of a combustion engine. 8. The converter device according to claim 7, wherein n is two or more. The method according to claim 1 or 2, An inlet part 2 for exhaust gas leading the exhaust gas to the first part 17a of the passage, and an outlet part 3 for the exhaust gas leading the exhaust gas to be discharged from the second part 17b of the passage. Include, The exhaust gas is guided through the passageway in a direction to flow first through the first portion 17a of the passage before flowing through the second portion 17b of the passage. Converter device installed. Converter device according to one of the preceding claims, characterized in that the flow path (13a, 13b) is contained in a separate and independent module (M). 11. Converter device according to claim 10, characterized in that the detachable module (M) comprises at least one end wall (6) of the casing (1).

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