DE102013111033B4 - Method and device for thermal management of a vehicle exhaust system - Google Patents

Abstract

Method for thermal management in an exhaust system (1) for a motor vehicle having an internal combustion engine (2), which exhaust system has a decoupling element (5 ', 5 ") with a flexible conduit element (5a) in the form of a bellows and with at least one in the flexible conduit element ( 5a) arranged inner component (5d) in the form of a winding tube for conducting a of the internal combustion engine (2) derived exhaust stream (P2), wherein the exhaust stream (P2) through the inner component (5d) is passed, characterized in that for the purpose of heating the exhaust gas stream (P2) a preheated gaseous medium separated from the exhaust gas flow (P2) outside the inner component (5d) via a gap (5e) between the flexible conduit member (5a) and the inner component (5d) through the decoupling element (5 ', 5 ") passed becomes.

Description

The invention relates to a method according to the preamble of claim 1 for a thermal management in an exhaust system for a motor vehicle with internal combustion engine.

Furthermore, the invention relates to a device for a thermal management in an exhaust system for a motor vehicle with an internal combustion engine.

Exhaust systems of the type mentioned regularly have at least one decoupling element (EKE), which has a flexible conduit element and at least one so-called inner component arranged in the flexible conduit element. The flexible conduit member is preferably formed as a (metal) bellows, while said inner component is regularly formed as a winding tube or liner. The inner component serves to guide an exhaust gas flow of the internal combustion engine within the decoupling element as well as for insulation and noise damping.

Recently, the thermal management in the exhaust system of a motor vehicle is becoming increasingly important. This is not least due to ever stricter emission standards (eg the EU6 standard), which make it necessary to provide additional functional elements or devices for exhaust gas purification within the exhaust system of an internal combustion engine, for example catalysts, particle filters or the like. To reduce the emission of nitrogen oxides (NO _x ) is also in modern internal combustion engines also regularly an exhaust gas recirculation used, which is one of the most important measures to reduce nitrogen oxide emissions, especially in diesel engines. In this case, part of the exhaust gas flow is returned to the combustion chamber of the internal combustion engine. Especially with diesel engines, the removal of this partial flow takes place behind the diesel particulate filter (DPF), since the exhaust gas recirculation takes place via a compressor, which must be protected against (soot) particles.

In particular, in connection with the exhaust gas recirculation solution approaches are known from the prior art, in which the exhaust gas recirculation line is guided via a separate, additional decoupling element to the engine. Such approaches are disadvantageous because regularly only very limited space for such exhaust gas recirculation lines is available. In addition, the said return lines are regularly lines with a relatively thin cross section, which then make correspondingly in the decoupling element to be provided a relatively thin, long bellows required. A production of such bellows is difficult and correspondingly expensive.

In addition, the known from the prior art exhaust gas recirculation lines act in practice as a cooling element, so that the exhaust gas cools strongly on the way back to the compressor or combustion chamber. This can lead to a sooting of parts of the exhaust gas recirculation, in particular of the compressor, and thus to damage of the same.

In addition, results in exhaust systems of modern motor vehicles in the above-mentioned exhaust problem, the particular difficulty that arranged in the exhaust system facilities for exhaust gas purification, such as the aforementioned catalysts and diesel particulate filter, a sufficiently high exhaust gas temperature need to meet their cleaning effect optimally. In particular, during the cold start of a motor vehicle and / or motor vehicles, which are equipped with an automatic start-stop, it is therefore often required in the prior art, preheat or heat the exhaust gas by means of an additional heater to meet the relevant emission standards permanently to be able to.

In the EP 1 770 250 A2 discloses a heat exchanger and a method for its production, wherein the heat exchanger has an inner corrugated hose line which is corrugated and extends concentrically to an outer sheath line, wherein in the outer flow space between the sheath line and the corrugated hose line spacers are arranged. In the process for the production of the heat exchanger, curved heat exchanger areas are created by thornless simultaneous forming of hose line and sheath line, in which the hose line and the sheath line change their axial extent direction.

In the EP 2 326 823 B1 there is shown a particulate trapping device disposed between an exhaust conduit having a flow pattern in a first main direction and an exhaust gas recirculation conduit. The exhaust pipe has a first central cross section, a first enlarged cross section and at least one partially permeable hollow body, which is arranged in the first enlarged cross section, wherein the at least one partially permeable hollow body defines with its wall a primary mold having an interior. The hollow body has two opposite open sides and is arranged so that it is flowed axially from one side.

In the DE 38 33 957 A1 a device for exhaust gas recirculation in diesel engines is described, in which an exhaust gas filter for the recirculated exhaust gas is arranged in a branching off from the exhaust gas Abgasrückrührleitung. This exhaust gas filter insert is arranged in the branch point of the exhaust gas recirculation line so that its dirt-side surface is approximately parallel to the flow direction of the main exhaust gas flow in the region and course of a normal wall-near flow line.

The FR 2 926 845 A1 discloses a motor vehicle with exhaust gas recirculation, for which purpose a flexible conduit element comprises two coaxial conduit elements. A main exhaust stream is passed through the interior of these conduit members, while a return flow is directed outwardly in an annular channel within the outer conduit member.

From the DE 42 05 496 C1 an exhaust system for an internal combustion engine is known in which an inner exhaust pipe is surrounded on the outside by a concentrically arranged bypass line. The bypass line shields the inner exhaust pipe, so that the latter is thermally insulated to the ambient temperature. In addition, it is described that the amount of exhaust gas flowing back in the bypass line is sufficiently cooled by heat emission to the environment in order to protect a catalyst from overheating.

The DE 10 2010 035 311 A1 shows a decoupling element, in which a division of the exhaust gas flow into two partial flows, of which the inner partial flow is passed through an inner winding tube. The outer partial flow flows between said inner coil tube and an outer coil tube concentrically surrounding the inner coil tube.

The DE 103 07 651 A1 discloses a bellows-shaped conduit element with filter element.

The invention is therefore based on the object to provide an efficient thermal management of an exhaust system for a motor vehicle with an internal combustion engine, so that while avoiding additional, costly components with the most efficient use of existing, scarce space, the possibility exists in the exhaust system provided exhaust gas cleaning facilities as efficiently as possible To comply with existing emission standards and at the same time to prevent damage to equipment of the exhaust system, in particular the compressor, and counteract.

These objects are achieved by a method having the features of claim 1 and by a device having the features of claim 9. Advantageous developments are the subject of claims.

According to the invention, a method for thermal management in an exhaust system for a motor vehicle with an internal combustion engine, which exhaust system is a decoupling element with a flexible conduit element in the form of a bellows and with at least one arranged in the flexible conduit member inner component in the form of a winding tube for conducting an originating from the engine exhaust stream wherein the exhaust gas flow is passed through the inner component, characterized in that for the purpose of heating the exhaust gas flow, a preheated gaseous medium separated from the exhaust gas flow outside the inner component via a gap between the flexible conduit member and the inner component is passed through the decoupling element, preferably as preheated gaseous medium hot exhaust gas of the internal combustion engine and / or by means of an optional heater preheated gaseous medium is used.

An inventive device for thermal management in an exhaust system for a motor vehicle with an internal combustion engine, which exhaust system comprises a decoupling element with a flexible conduit element, preferably bellows, and with at least one arranged in the flexible conduit member inner component, preferably winding tube, for conducting an originating from the engine exhaust stream , wherein the flexible conduit member is a bellows and the inner component is a winding tube, is characterized by a conduit means for directing a portion of the exhaust stream separated from the exhaust stream by the decoupling element, the conduit means comprising and at least a portion between the flexible conduit member and the inner component of the decoupling member is partially formed as another winding tube.

It is therefore intended according to the invention to provide a conduit means for directing a portion of the exhaust stream and a preferably preheated gaseous medium separate from the exhaust stream through the decoupling element.

It is therefore intended to additionally use the decoupling element provided regularly in the exhaust gas system of a motor vehicle either for exhaust gas recirculation and / or for passing a gaseous medium for heating the exhaust gas flow. In this way, on the one hand to an additional decoupling for the Exhaust gas recirculation are completely eliminated, which has a positive effect in terms of cost and space utilization. Due to the fact that the decoupling element, which serves primarily for passing the hot exhaust gas flow, is also used for the exhaust gas recirculation, excessive cooling of the recirculated exhaust gas can be counteracted and the aforementioned problem of sooting can be effectively avoided. Due to the continued possibility of heating the exhaust gas stream by means of the passage of a preheated gaseous medium (preheating medium) through the decoupling element, it is also possible to ensure that the abovementioned exhaust gas purification devices can operate optimally efficiently. All these advantages arise in synergetic manner due to the proposed multiple use of the exhaust system of a motor vehicle with internal combustion engine regularly present decoupling element.

For the purpose of exhaust gas recirculation to a device arranged upstream of the decoupling element, preferably to a combustion chamber of the internal combustion engine, most preferably via an exhaust gas cooler and / or a compressor, in a further development of the method according to the invention, a part of the exhaust gas stream is branched off downstream of the decoupling element and separated from the exhaust gas flow outside the inner component be recirculated through a gap between the flexible conduit member and the inner component by the decoupling element to said device.

The inventive method provides that the exhaust gas recirculation and / or the passage of the preheating medium takes place in a region between the flexible conduit element and the inner component of the decoupling element.

The device according to the invention is accordingly characterized in that the conduit means comprises a free region between the radially outer flexible conduit element and the radially inner component of the decoupling element, through which region the recirculated partial exhaust gas flow and / or the gaseous medium are conducted ,

An advantageous development of the method according to the invention provides that the exhaust gas recirculation and / or the passage of the preheating medium takes place via at least one additional line section within the decoupling element. This additional line route is preferably formed at least partially flexible and may in this context comprise a winding tube, a (metal) bellows and / or a pipe element (flame tube).

A corresponding development of the device according to the invention is characterized in that the line device comprises at least one additional line route for the partial exhaust gas flow and / or the preheating medium.

It can be provided that the additional line section has a different from the inner component of the decoupling element cross-section. Preferably, the cross section of the additional line path is smaller than the cross section of the inner component.

Yet another development of the method according to the invention provides that the passage of the preheating medium takes place in the flow direction of the exhaust gas flow through the decoupling element. Alternatively, however, it can also be provided that the passage of said medium opposite to the flow direction of the exhaust gas flow takes place through the decoupling element.

A corresponding development of the device according to the invention provides that the conduit means for a passage of the preheating medium in the flow direction of the exhaust gas flow through the decoupling element or - alternatively - is designed for a passage of the preheating medium opposite to the flow direction through the decoupling element.

In the course of another development of the device according to the invention can be provided that the conduit means cooperates with an exhaust valve or the like to return a portion of the exhaust gas flow through the decoupling element. Such an exhaust flap or a comparable device is advantageously arranged downstream of the decoupling element in the exhaust gas stream and can ensure that a part of the exhaust gas flow is selectively returned to the internal combustion engine through the decoupling element. In this case, according to the invention, the exhaust gas recirculation or recirculation can take place either through a free region between inner component and flexible conduit element of the decoupling element, or via an additional line route within the decoupling element, as has already been pointed out in detail.

Yet another development of the device according to the invention provides that the line device is in operative connection with a device arranged upstream of the decoupling element, preferably a combustion chamber of the internal combustion engine. Most preferably, said active compound is a Exhaust gas cooler and / or a compressor (compressor). Additionally or alternatively, it can be provided that the conduit device is in operative connection with a separate heating device for preheating the gaseous medium.

It can also be provided that the decoupling element has a round cross-section. Alternatively, it can also be provided that the decoupling element has an approximately oval cross-section. Especially in the latter case it can be provided, without limitation, that the additional line route, if present, is guided parallel to the inner component by the decoupling element.

Yet another development of the device according to the invention provides that the line device for the partial exhaust gas flow, which is returned to the internal combustion engine, and for the preheating medium has separate flow guides. For example, separate additional line sections can be provided both for the partial exhaust gas flow as well as for the medium. Alternatively, however, it is also possible to lead the partial exhaust gas stream or the medium over an additional line route, while the respective other stream (partial exhaust gas stream or medium) is guided over the free region between the flexible line element and inner component of the decoupling element. Furthermore, it is of course also possible to guide the partial exhaust gas flow and the medium alternately via a single flow guide. This flow guidance can then be realized either over the free region between the flexible conduit element and the inner component of the decoupling element or through an additional conduit route within the decoupling element.

Yet another development of the device according to the invention provides that the flexible conduit element is provided on the input side and / or output side with a perforated plate, which perforated plate has at least two holes. In this way, further line elements of the exhaust system, in particular rigid pipe elements, can be connected in fluidic operative connection to the decoupling element. Depending on the other configuration of the device, one of the two holes is in fluidic operative connection with the inner component of the decoupling element. The other of the two holes is correspondingly in fluidic operative connection with the free area between the flexible conduit element and the inner component of the decoupling element or with the mentioned additional conduit route, if present. Of course, said perforated plate may also have more than two holes, for example, if the exhaust gas recirculation over said space between the flexible conduit member and inner component and if in addition for the passage of the preheating medium, an additional line route is present.

However, the invention is by no means limited to such a configuration: For example, each additional line sections may be present for both the exhaust gas recirculation and for the preheating medium, which correspond with corresponding holes of the perforated plate. Furthermore, it is also possible to guide the preheating medium over the region between the flexible line element and the inner component of the decoupling element, while the exhaust gas recirculation takes place via an additional line route.

The connection of said further line elements to the perforated plate can be done for example by material connection, preferably welding.

In order to avoid thermal stresses, another development of the device according to the invention provides that a thermal expansion element is arranged between the decoupling element and the device arranged upstream of the decoupling element, in particular the exhaust gas cooler. However, it is also possible that due to the device according to the invention at the said point to a stretching body can be completely dispensed with, because all thermal stresses are absorbed or reduced by the decoupling element.

In order to avoid that the inner component of the decoupling element and an optionally existing additional line run against each other in operation of the motor vehicle due to vibrations or other movements, provides a particularly advantageous development of the device according to the invention that between the inner component and the additional line route at least one support element is arranged , This support element may for example consist of wire mesh material or the like, wherein it is crucial that the material used withstands the given thermal load. Preferably, such a support element may be formed in an eight-shaped, annular or in the form of a ring segment. In the case of an eight-shaped configuration, the support element advantageously surrounds both the inner component and the additional line section circumferentially. In the case of an annular configuration, the support element can be arranged around the inner component and / or around the additional line section, in particular also alternately.

In the context of the present invention, the exhaust gas recirculation can take place via a rigid pipe element between the decoupling element and the internal combustion engine.

Although the presence of an additional line section of the decoupling element can be advantageous in terms of flow, in particular due to the provided exhaust flap when using the intermediate space between flexible line element and inner component of the decoupling element for the exhaust gas recirculation due to the reduced flow of the exhaust gas within the Innenkomponenente with little or no counterflow / Verwirbelung in said space and corresponding pressure loss to be expected, so that said space for the exhaust gas recirculation (or alternatively for the passage of the preheating medium) is also opposite to the flow direction of the exhaust gas flow in each case.

Of course, the present invention is not limited to the fact that inside a cross-sectionally oval Entkoppelelements mandatory two inner liner or inner components (coiled tubing) must be used. Even within an oval decoupling element, it is possible, in particular to guide the exhaust gas recirculation and / or the preheating medium over the intermediate space between the inner component and the flexible conduit element.

Furthermore, it is not necessary in the context of the present invention for the preheating medium to be a separate medium which is preheated by means of a separate heating device. As the skilled artisan easily recognizes, it is within the scope of the present invention to use as the preheated gaseous medium hot exhaust gas of the internal combustion engine, in particular before this exhaust gas purification devices of the exhaust system flows through and has cooled down accordingly.

In another embodiment of the invention, a filter element for filtering a recirculated exhaust gas partial flow is arranged in or following the decoupling element, which is in contact with the conduit means. In this way, soot and metallic and ceramic particles entrained in the recirculated exhaust gas flow can be filtered and thus damage to engine-side parts such as exhaust gas cooler, compressor and ultimately the internal combustion engine can be prevented.

Preferably, the filter element is designed such that it filters particles from a size of at least 200 microns from the recirculated exhaust gas partial stream.

The filter element can be arranged within the decoupling element in front of an outlet for a recirculated partial exhaust gas stream. In this way, production residues, which may be present in the flexible conduit element and there are technically difficult or impossible to remove, are filtered out, so that it is prevented that they get into a motor-side exhaust gas recirculation line.

In a further advantageous embodiment of the invention may be provided before or after the decoupling element, in particular between the decoupling element and at least one downstream exhaust gas purification device, a double-walled pipe having an inner tube and a coaxially disposed around the inner tube outer tube, wherein the inner tube with the Inner component and an annular gap between the two tubes with said conduit means ( 5e ) are in fluidic operative connection. Such a coaxial construction achieves an improved insulation effect and reduces cooling, in particular during start / stop operation, so that no additional insulation measures are required despite "off-engine" housing of the exhaust gas purification device, such as diesel particulate filter and / or catalytic converter.

In addition, an expansion element for compensating thermal changes in length can be provided in one or in both of the coaxial tubes of the double-walled pipe.

• 1 zeigt schematisch anhand eines Blockschaltbildes eine Abgasanlage gemäß dem Stand der Technik;
• 2 zeigt eine erfindungsgemäße Vorrichtung gemäß einer Ausführungsform;
• 3 zeigt eine erfindungsgemäße Vorrichtung gemäß einer weiteren Ausführungsform;
• 4 zeigt einen Querschnitt durch eine erfindungsgemäße Ausführungsform im Wesentlichen gemäß 2;
• 5 zeigt einen teilweisen Längsschnitt durch eine erfindungsgemäße Ausführungsform im Wesentlichen gemäß 2;
• 6 zeigt einen Querschnitt durch eine andere erfindungsgemäße Ausführungsform;
• 7 zeigt einen teilweisen Längsschnitt durch die Ausführungsform gemäß 6;
• 8 zeigt ein weiteres Ausführungsbeispiel der Erfindung in einer schematischen Schnittzeichnung und
• 9 zeigt ein Ausführungsbeispiel eines ovalen Entkoppelelements mit integrierter Abgasrückführung.

Further features and advantages of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawing.

• 1 schematically shows a block diagram of an exhaust system according to the prior art;
• 2 shows a device according to the invention according to an embodiment;
• 3 shows a device according to the invention according to a further embodiment;
• 4 shows a cross section through an embodiment of the invention substantially according to 2 ;
• 5 shows a partial longitudinal section through an embodiment of the invention substantially according to 2 ;
• 6 shows a cross section through another embodiment of the invention;
• 7 shows a partial longitudinal section through the embodiment according to 6 ;
• 8th shows a further embodiment of the invention in a schematic sectional drawing and
• 9 shows an embodiment of an oval decoupling element with integrated exhaust gas recirculation.

1 schematically shows a block diagram of the exhaust system of a motor vehicle with internal combustion engine according to the prior art, which exhaust system in its entirety by the reference numeral 1 is designated. The actual internal combustion engine is at reference numerals 2 shown, reference numerals 3 denotes a combustion chamber of the internal combustion engine. According to the arrow P1 Exhaust gas comes out of the internal combustion engine 2 over a turbocharger 4 and continue according to the arrow P2 to a decoupling element made in a conventional manner 5 , Which is designed here as a metallic corrugated hose or bellows with knitted outer component and winding tube or inner liner for flow guidance. Such decoupling elements are known to the skilled person in many ways. The decoupling element 5 has a circular cross-section. It is used in particular for the mechanical decoupling of downstream parts of the exhaust system 1 to vibrations of the internal combustion engine 2 ,

According to arrow P3 the exhaust gas reaches behind the decoupling element 5 via an underbody DPF (Diesel Particulate Filter) 6 to an exhaust flap 7 in which a partial exhaust gas flow according to arrow P4 ' branched off and to the internal combustion engine 2 is returned. This will be discussed in more detail later. The main exhaust flow is indicated by arrow P4 about further, not explicitly drawn line elements / exhaust gas purification elements from the exhaust system 1 pushed out.

The partial exhaust gas flow P4 ' passes through a low-pressure exhaust gas recirculation line 8th (ND-EGR path) to another decoupling element 9 , which is analogous to the decoupling element 5 is constructed, but it regularly has a smaller cross-section and a relatively large length. Such decoupling elements 9 are relatively expensive to produce and therefore relatively expensive. In addition, in that area of a motor vehicle, in particular in the underbody area, in which the exhaust system 1 and especially the decoupling element 9 is typically arranged, only little space available, so that already the presence of the decoupling element 9 construction space technology has a negative effect. According to the arrow P5 the recirculated partial exhaust gas flow reaches an exhaust gas cooler 10 and from there via a compressor 11 back to the combustion engine 2 or in the combustion chamber 3 , what in 1 is shown only schematically.

In addition to the already mentioned, disadvantageous consuming design of the exhaust system 1 according to 1 , in particular, it should be noted that due to the relatively long distance 8th , the decoupling element 9 and due to the fact that the partial exhaust gas flow according to arrow P4 'to protect the compressor 11 only behind the DPF 6 can be diverted, there is the risk of sooting of components of the return path, in particular the decoupling element 9 , the cooler 10 and the compressor 11 ,

The following figures show preferred embodiments of the invention, wherein like reference numerals designate the same or equivalent elements.

In 2 an embodiment of a device according to the invention for the thermal management in the exhaust system of a motor vehicle with an internal combustion engine is shown, wherein here and in the following only the parts of the exhaust system essential for the understanding of the invention are explicitly shown. reference numeral 2 again denotes an internal combustion engine whose hot exhaust gases according to the arrow P1 . P2 to a particularly designed decoupling element 5 ' which will be discussed in more detail below. Of course, the interposition of a turbocharger according to 1 possible, in 2 but not shown for reasons of clarity.

The decoupling element 5 ' has in a conventional manner a flexible conduit element in the form of a corrugated hose or metal bellows 5a on, of an outer component in the form of a metal mesh 5b is surrounded. The metal bellows 5a has unrecognizable smooth cylindrical terminal ends, and the knitwear 5b is in the area of these terminal ends in a conventional manner under end sleeves 5c involved. Within the arrangement described is concentric with the metal bellows 5a an inner component in the form of a winding tube 5d arranged, by which according to the arrow P2 that of the internal combustion engine 2 originating exhaust gas flow is guided. On the representation of the DPF 6 (see. 1 ) at the output end of the decoupling element 5 ' was omitted for reasons of clarity. Shown again is the main exhaust stream P4 from which the recirculated partial exhaust gas flow P4 'has been branched off. This branch can basically according to 1 be accomplished by means of an exhaust valve or a similar device.

It is essential that the object of the 2 the exhaust gas recirculation line 8th' (in 2 dashed lines) not via a separate component but via the decoupling element 5 ' is guided, namely over or through the gap 5e between the flexible conduit element 5a and the winding tube 5d , About the mentioned gap 5e the partial exhaust gas flow P4 'becomes the internal combustion engine 2 recycled. Of course, the decoupling element 5 ' for the exhaust gas recirculation still further device downstream, in particular the in 1 illustrated cooler 10 and / or compressors 11 , what a 2 for reasons of clarity are not shown.

Optionally, in the embodiment according to 2 within the flexible conduit element 5 ' still a second interior component 5f be used in the form of a winding tube or the like, which the metal bellows 5a and so on for improved flow guidance within the gap 5e can care what gap 5e then between the winding tube 5d inside and the winding hose 5f is defined outside.

Upstream and downstream of the decoupling element 5 ' according to 2 suitable connection parts are to be provided which, on the one hand, initiate or discharge the (main) exhaust gas flow into and out of the inner component 5d on the other hand, conversely, for introducing the recirculated exhaust gas flow into and out of the gap 5e are suitable. As such, these fittings are not subject of the present invention.

The return of the partial exhaust gas flow between the decoupling element 5 ' and the internal combustion engine 2 can be realized in particular by means of rigid pipe elements (not shown). In order to thermal stresses, especially in the area between the decoupling element 5 ' and the downstream exhaust gas cooler 10 (see. 1 ), it may be provided to arrange in this area at least one thermal expansion body, which is in 2 also not explicitly shown for reasons of clarity.

It is not necessary for the flow guidance within the decoupling element 5 ' to provide exclusively continuous flexible elements in the form of winding tubes or the like. In particular, it is in modification of the illustration in 2 possible, both the interior component 5d as well as the optional further interior component 5f partially rigid, ie form as a pipe element or flame tube. An at least partial embodiment in the form of a corrugated hose or bellows is possible. This also applies accordingly to all other embodiments of the invention shown.

Finally, in 2 at reference numerals 12 schematically an optional heater, such as a burner or the like, shown, which can be used in the course of an extremely efficient thermal management of the exhaust system to a preheated gaseous medium, such as air, through the gap 5e to guide in this way the exhaust stream or the exhaust gas according to arrow P2 to warm up. This may be of particular importance if the fulfillment of strict exhaust emission standards (for example EU6) even in the case of a cold start and / or in the presence of an automatic start-stop system is required for the decoupling element 5 ' downstream exhaust gas purification facilities, such as a DPF or a catalyst, always work as efficiently as possible. When using the illustrated decoupling element 5 ' is it possible the gap 5e in the manner already mentioned to use for heating the exhaust gas stream. It is basically not necessary, the preheated gaseous medium (also referred to as preheating medium) according to the arrow P4 'opposite to the exhaust stream P2 through the decoupling element 5 ' to lead. Also, a same direction of flow through the decoupling element 5 ' is possible. In particular, it is also possible the gap 5e selectively, in particular alternately, to use either for the passage of said preheating medium or for exhaust gas recirculation, for which then corresponding switching elements (not shown) would be provided. It is also not necessary in this context, said preheating medium by means of a separate heater 12 to heat. As in 2 represented by a dot-dashed arrow, the preheating medium can also directly from the engine 2 come. In particular, hot exhaust gas from the internal combustion engine can be used as a preheating medium in this connection. In this context, it is of course not necessary, the preheating medium opposite to the exhaust gas flow direction indicated by arrow P2 through the decoupling element 5 ' to lead. Of course, it is also possible, the preheating medium selectively from the engine 2 and the heater 12 to acquire.

The heater 12 and the internal combustion engine 2 Accordingly, in the following embodiments according to the 3 ff. be present; their representation is omitted below only for the sake of clarity of drawing.

3 shows another embodiment in which the decoupling element 5 ' preferably has an oval cross-sectional shape, see. for example 6 , The interior component 5d , which the exhaust gas flow according to arrow P2 is, according to 3 Off-center with respect to the flexible conduit element or metal bellows 5a arranged. Parallel to the inner component 5d , which in turn is designed here as a winding tube, is another inner component in the form of an additional winding tube 5g provided, which further winding tube 5g parallel to the former winding tube 5d through the decoupling element 5 ' is guided. The winding tube 5g has a smaller diameter than the winding tube 5d and serves according to arrow P4 'in particular for guiding the recirculated partial exhaust gas flow (see. 2 ). Again, optionally, another interior component 5f be provided, which the metal bellows 5a lining.

reference numeral 5h denotes spacers or spacers which may be in the form of wire knit elements. Again 3 it can be seen, are the spacers 5h each between adjacent internal components 5d . 5f . 5g arranged to prevent a counter-beating of said inner components in the operation of the exhaust system. The spacers can be designed as individual, separate knitted cushions. In addition, an annular or eight-shaped configuration of the spacer elements is possible, cf. 6 , Over the longitudinal extent of the decoupling element 5 ' Can a variety of spacers 5h be used. These need not be arranged at identical axial positions (with separate execution of the individual spacers between the Innenkomponeneten). Instead of wire mesh or the like, any other suitable, temperature and friction resistant material may be used to make the spacers.

As based on 2 has already been executed, the additional internal component 5g be used in the course of an efficient thermal management for preheating and heating the exhaust gas flow. Finally, the additional interior component takes over 5g according to 3 the function of the gap 5e according to 2 , so that reference can be made to the relevant statements.

The supply and discharge of the relevant gas flows takes place at the decoupling element 5 ' according to 3 about this suitable fittings, which in turn are not shown explicitly. For example, in the area of end sleeves 5c the decoupling element 5 ' the provision of orifices (not shown) may be provided, corresponding to a (larger) hole in fluidly operative connection with the inner component 5d and a (smaller) hole in fluid communication with the further interior component 5g can have.

4 shows the decoupling element 5 ' essentially according to 2 in cross-section, so that in this case only to peculiarities of the representation in 4 is to be entered more precisely. reference numeral 5i designated distributed over the circumference of the inner component 5d arranged spacer elements, for example in the form of knitted elements or the like, which for a defined-central arrangement of the inner component 5d within the clear bellows cross-section. With reference numerals 5a ' is a so-called bellows tube shown, which are the already mentioned above smooth cylindrical connecting ends of the bellows 5a is. Preferably, said spacers are located 5i especially in the area of these smooth-cylindrical connection ends or bellows tubes 5a ' and provide in this way for the illustrated central arrangement of the exhaust-carrying inner component 5d , In this case, the spacer elements 5i between the inner component 5d and the optional other interior component 5f which the bellows 5a be arranged, as shown.

5 shows a longitudinal section of a partial section of the embodiment according to FIG 2 , In addition, located at reference numerals 5h an example annular spacer or spacer, which or which prevents the operation of the exhaust system that the inner component 5d against the lining inner component 5f or the metal bellows 5a suggests. Otherwise, the illustration corresponds to 5 those in 2 ,

6 shows a cross section through an oval decoupling element 5 ' which essentially corresponds to the embodiment according to FIG 3 equivalent. Well recognizable here is the eight-shaped configuration of the spacers (knitted rings) 5h , These may be designed as a single, continuous element or in the form of two separate annular elements. Otherwise, the components and functions correspond to the description of the 3 , Analogous to the description of the 4 reference numeral 5a "denotes a smooth, oval terminal end of the bellows 5a , which is also designed accordingly oval.

How to especially the 6 removes, remains outside the internal components 5d . 5g still a (residual) free space 5e, which in principle can also be used in the context of the invention for media management. So it is in the embodiment according to 6 especially possible, the inner component 5d to use with the larger cross-section for the main exhaust system, while the inner component 5g is used with the smaller cross section for exhaust gas recirculation. In addition, it would then be possible in the area of open space 5e a preheating medium of the type already mentioned by the decoupling element 5 ' conduct. In principle, it would also be possible to use the functions of the interior component 5g and the free space 5e to swap.

Finally shows 7 still a partial section of the embodiment in 3 , For details, see the description there.

Another embodiment of an exhaust gas recirculation according to the invention is shown in FIG 8th shown in a schematic sectional drawing. Here is an exhaust gas coming from an internal combustion engine P2 by a decoupling element 5 ' and a connected pipe 15 to an exhaust gas purification device such as a diesel particulate filter 6 directed. On the input side is the decoupling element 5 ' motor-mounted, while the output side, the continuing pipeline 15 and the subsequent diesel particulate filter 6 for example by means of a holder 13 are mounted frame-mounted. The decoupling element therefore serves to decouple the engine movements of the frame and vehicle body.

At or behind the diesel particulate filter 6 a partial flow P4 'is branched off and returned to the internal combustion engine. The return takes place according to the invention also by decoupling element 5 ' separated from the exhaust stream P2 , For this purpose, the decoupling element 5 ' similar to the one in 2 shown embodiment designed such that for the exhaust gas recirculation, a gap 5e between a flexible conduit element 5a and a flow-guiding inner component, such as a winding tube 5d can be used.

The decoupling element 5 ' points as in 2 shown a ring-corrugated metal bellows 5a and a winding tube disposed inside the metal bellows 5d on. The winding tube 5d is via connection boards 5c on the engine side with an exhaust pipe coming from the combustion engine and on the output side with the diesel particulate filter 6 leading exhaust pipe 15 connected, so that an exhaust gas coming from the engine P2 inside the winding tube 5e guided and as by arrow P3 indicated is forwarded to the diesel particulate filter.

The return of the partial exhaust gas flow P4 ' takes place as already described by the gap 5e between the metal bellows 5a and the winding tube 5d , The introduction takes place via a coaxial around the exhaust pipe 15 lying outer tube 16 with a corresponding inlet 17 , The outer tube 16 is with a smooth cylindrical connection end 5 m the metal bellows 5a connected. The connection end 5 m is optional with a perforated perforated plate 5n provided by the recirculated exhaust gas partial stream P4 ' in the gap 5e can flow. In the outer tube 16 is optional an expansion element 14 integrated, which is used for thermal expansion compensation between the two coaxial tubes 15 and 16 serves. As an expansion element 16 For example, a number of bellows shafts may be used which are molded or welded into the pipeline.

The coaxial pipes 15 . 16 thus form a double-walled connecting line between the diesel particulate filter 6 and decoupling element 5 ' , in the interior of which the exhaust gases coming from the internal combustion engine are guided, while the outer annular gap between the coaxial tubes 15 . 16 is used for exhaust gas recirculation. The double-walled connecting line thus sets the operating principle of the decoupling element 5 ' until exhaust gas cleaning in the diesel particulate filter 6 and / or a catalyst. In this way, an improved insulation effect is achieved on this route and cooling, especially in the start / stop operation is reduced, so that no additional insulation measures are required despite the "remote engine" arrangement of the diesel particulate filter.

On the opposite side of the metal bellows ends 5a on a bellows tube 5a ' , on which an outlet laterally 5l is appropriate. The outlet 5l is connected to the engine-side low-pressure return line. In front of the outlet 5l is a filter element 5k arranged. It serves to in the recirculated exhaust gas flow P4 ' entrained particles such as from catalyst or diesel particulate filter derived metallic and ceramic particles to filter. Through micro cracks in the particle filter 6 or via a leakage current passing through the windings of the winding tube 5d in the gap 5e between metal bellows 5a and winding tube 5d penetrates, can in the exhaust stream P4 ' Also be included soot particles by filter element 5k be filtered out. Especially in case of failure of the diesel particulate filter otherwise larger amounts of soot could get into the exhaust gas recirculation. Even manufacturing residues in the bellows shafts themselves can cause problems if they get into the exhaust gas recirculation. Through the filter element 5k This prevents damage to the downstream exhaust gas cooler, compressor and ultimately the internal combustion engine.

The filter element 5k may for example be formed by a filter made of a metal mesh, metal tresses or metal mesh. The filter element 5k can also be designed as a ring filter. Due to the position close to the engine, the temperatures remain high enough to ensure a continuous regeneration of the filter element, so that it does not cause clogging or fouling of the filter element 5k can come.

Instead of a side outlet 5l Again, a double-walled pipe can be installed here, similar to the one on the downstream side. In this case, a filter element can, for example, be arranged annularly in the connection area between the decoupling element and the upstream double pipeline.

Alternatively, the decoupling element also as in the 3 . 6 or 7 be executed. 9 shows an embodiment of a decoupling element 5 ' with oval cross-section. The decoupling element 5 ' has frontal round connection shelves 5c . 5c ' for an exhaust pipe and offset in oval cross section arranged thereto connecting piece 51 . 51 ' for a recirculated exhaust gas flow P4 . P5 ,

connection Borde 5c . 5c ' and connecting pieces 51 . 51 ' are via a corresponding transition piece with an oval bellows 5a the decoupling element 5 ' connected. The oval bellows 5a is shown here only schematically. Inside is a winding tube 5d arranged with a circular cross-section, which the connecting rims 5c . 5c ' connects together and the exhaust stream P2 . P3 passes. The connecting pieces 51 . 51 ' flow into a gap 5e between the oval corrugated bellows 5a and the circular winding tube 5d ,

The connection board 5c is connected to the exhaust pipe coming from the engine, eg the exhaust manifold. To the connection board 5c ' the exhaust pipe leading to the particle filter or catalytic converter is connected. At the connection branch 51 ' an exhaust gas recirculation line is connected, which is a purified partial exhaust gas stream P4 ' from the particulate filter or catalyst leads back to the engine. The recirculated exhaust gas partial stream P4 ' flows in the gap 5e between corrugated bellows 5a and inner winding tube 5d to the engine side connection benefit 51 to which the exhaust gas recirculation line leading to the engine is connected.

In the gap 5e , which due to the oval cross-section of the bellows 5a is quite large, is in front of the outlet 5l a filter element 5k arranged. This can be designed as a filter bag, filter cone or filter calotte. The through the filter element 5k passed through, purified partial flow P5 is then added to the combustion air of the engine.

Schematically indicated in 9 in addition, that through the windings of the winding tube 5d a low leakage current P4 " in the gap 5e can flow, the soot particles could enter into the exhaust gas recirculation. These are through the filter element 5k as well as possible others in the exhaust partial flow P4 ' retained entrained particles.

Claims (28)

Method for thermal management in an exhaust system (1) for a motor vehicle having an internal combustion engine (2), which exhaust system has a decoupling element (5 ', 5 ") with a flexible conduit element (5a) in the form of a bellows and with at least one in the flexible conduit element ( 5a) arranged inner component (5d) in the form of a winding tube for conducting a of the internal combustion engine (2) derived exhaust stream (P2), wherein the exhaust stream (P2) through the inner component (5d) is passed, characterized in that for the purpose of heating the exhaust gas stream (P2) a preheated gaseous medium separated from the exhaust gas flow (P2) outside the inner component (5d) via a gap (5e) between the flexible conduit member (5a) and the inner component (5d) through the decoupling element (5 ', 5 ") passed becomes. Method according to Claim 1 in which hot exhaust gas of the internal combustion engine (2) and / or gaseous medium preheated by means of an optional heating device (12) is used as the preheated gaseous medium. Method according to Claim 1 or 2 in which, for the purpose of exhaust gas recirculation to a device arranged upstream of the decoupling element (5 ', 5 "), a part (P4') of the exhaust gas flow (P2) is branched off downstream of the decoupling element (5 ', 5") and separated from the exhaust gas flow (P2) outside the inner component (5d) is returned to said device via a gap (5e) between the flexible conduit element (5a) and the inner component (5d) through the decoupling element (5 ', 5 "). Method according to Claim 3 , characterized in that the exhaust gas recirculation to a combustion chamber (3) of the internal combustion engine, preferably via an exhaust gas cooler (1) and / or a compressor (11). Method according to Claim 3 or 4 , characterized in that the exhaust gas recirculation via at least one additional line section (5g), preferably winding tube, bellows and / or pipe element, by the decoupling element (5 ', 5 ") takes place. Method according to at least one of Claims 1 to 5 , characterized in that the passage of the medium via at least one additional line section (5g), preferably winding tube, bellows and / or pipe element, by the decoupling element (5 ', 5 ") takes place. Method according to at least one of Claims 1 to 6 , characterized in that the passage of the medium in the flow direction (P2) of the exhaust gas flow through the decoupling element (5 ', 5 ") or opposite to the flow direction (P2) of the exhaust gas flow through the decoupling element (5', 5"). Method according to one of Claims 3 to 5 in which the recirculated portion (P4 ') of the exhaust gas flow is filtered by means of a filter arranged in the decoupling element. Device for thermal management in an exhaust system (1) for a motor vehicle having an internal combustion engine (2), which exhaust system has a decoupling element (5 ', 5 ") with a flexible conduit element (5a) and with at least one interior component (5d) arranged in the flexible conduit element for conducting an exhaust gas stream (P2) originating from the internal combustion engine (2), the flexible conduit element (5a) being a bellows and the inner component (5d) being a winding tube, characterized by conduit means (5e, 5g) for guiding a part (P4 ') of the exhaust gas stream separated from the exhaust gas flow (P2) by the decoupling element (5', 5 "), wherein the conduit means a portion (5e) between the flexible conduit member (5a) and the inner component (5d) of the decoupling element (5 ', 5 ") and at least partially as a further winding tube (5g) is formed. Device after Claim 9 , characterized in that the conduit means (5e, 5g) is further adapted to conduct a preferably preheated gaseous medium separate from the exhaust stream (P2) by the decoupling element (5 ', 5 "). Device after Claim 9 or 10 characterized in that the conduit means (5e, 5g) cooperate with an exhaust flap (7) or the like to redirect the portion (P4 ') of the exhaust gas flow through the decoupling element (5', 5 "). Device according to at least one of Claims 9 to 11 , characterized in that the conduit means comprise at least one additional line section (5g) for the partial exhaust gas stream (P4 ') and / or the medium, preferably winding tube, bellows and / or pipeline element, which additional line route (5g) preferably one of the inner component (5d) has different cross-section, most preferably one with respect to the inner component smaller cross-section. Device according to at least one of Claims 9 to 12 , characterized in that the conduit means (5e, 5g) is in operative connection with a device upstream of the decoupling element (5 ', 5 "), preferably a combustion chamber (3) of the internal combustion engine (2), most preferably via an exhaust gas cooler (10 ) and / or a compressor (11), and / or that the conduit means (5e, 5g) is in operative connection with the combustion chamber (3) of the internal combustion engine (2), preferably as a preheated gaseous medium hot exhaust gas of the internal combustion engine (2) used is, and / or with a separate heater (12) for preheating the gaseous medium. Device according to at least one of Claims 9 to 13 , characterized in that the decoupling element (5 ') has a round cross-section. Device according to at least one of Claims 9 to 13 , characterized in that the decoupling element (5 ") has an approximately oval cross-section, wherein preferably the additional line path (5g) is guided parallel to the inner component (5d). Device according to at least one of Claims 9 to 11 , characterized in that the conduit means (5e, 5g) for the partial exhaust gas flow (P4 ') and the medium having separate flow guides or that the partial exhaust gas flow (P4') and the medium are guided alternately via a single flow guide. Device according to at least one of Claims 9 to 16 , characterized in that the conduit means (5e, 5g) for the passage of the medium in the flow direction (P2) of the exhaust gas flow through the decoupling element (5 ', 5 ") or for the passage of the medium opposite to the flow direction (P2) of the exhaust gas flow through the Decoupling element (5 ', 5 ") is formed. Device according to at least one of Claims 9 to 17 , characterized in that the flexible conduit member (5a) on the input side and / or output side (5a ', 5a ") is provided with a perforated plate, which perforated plate has at least two holes, so that further line elements of the exhaust system (1) in fluidly operative connection to the decoupling element (5 ', 5 ") are connectable. Device according to at least one of Claims 9 to 18 , characterized in that at least between the decoupling element (5 ', 5 ") and arranged upstream of the decoupling element means a thermal expansion body is arranged. Device according to at least Claim 12 , characterized in that between the inner component (5d) and the additional line section (5g) at least one support element (5h) is arranged, preferably made of wire knit material or the like, which support element (5h) is most preferably eight-shaped, annular or formed as a ring segment , Device according to at least one of Claims 9 to 20 in which a filter element (5k) for filtering a recirculated partial exhaust gas flow (P4 ') is arranged in or following the decoupling element (5'), which is in contact with the conduit device (5e). Device after Claim 21 in which the filter element (5k) is designed to filter particles of at least 200 μm in size from the recirculated partial exhaust gas flow (P4 '). Device after Claim 21 or 22 in that the filter element (5k) is arranged inside the decoupling element (5 ') in front of an outlet (51) for a recirculated partial exhaust gas flow (P4'). Device according to one of Claims 21 to 23 in which the filter element (5k) is designed as a ring filter. Device according to one of Claims 21 to 23 in which the filter element is designed as a filter bag, filter cone or filter calotte. Device according to one of Claims 21 to 25 in which the filter element (5k) consists of a metal mesh, metal ropes or metal knits. Device according to one of Claims 9 to 26 in which, before or after the decoupling element (5 '), in particular between the decoupling element (5') and at least one downstream exhaust gas purification device (6), a double-walled pipeline with an inner tube (15) and a coaxial around the inner tube (15) is provided, wherein the inner tube (15) with the inner component (5d) and an annular gap between the two tubes (15, 16) with the said conduit means (5e) are in fluidly operative connection. Device after Claim 27 in which one or both of the tubes (15, 16) of the double-walled pipeline an expansion element (14) is provided for the compensation of thermal changes in length.

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