DE102021134108A1 - vehicle exhaust system - Google Patents

Abstract

A vehicle exhaust system (10) has a section (14) close to the engine with an exhaust system component (26) close to the engine, a section (16) remote from the engine with an exhaust system component (28) remote from the engine and an intermediate pipe (22) connecting the exhaust system component (26) close to the engine with the engine remote exhaust system component (28) connects. The intermediate pipe (22) has one or more soundproofing openings (24). The vehicle exhaust system (10) further includes an intermediate tube shell (34) which defines a chamber (36) between itself and the intermediate tube (22). The intermediate pipe (22) is connected in terms of flow to the chamber (36) via at least one of the sound-damping openings (24). Furthermore, the intermediate tube sleeve (34) has a ventilation opening (40) via which the chamber (36) is fluidically connected to the section (16) remote from the engine.

Description

The invention relates to a vehicle exhaust system according to the preamble of claim 1.

Vehicle exhaust systems are well known and are used in automobiles, rail vehicles or ships to direct hot exhaust gases generated by an engine through various exhaust system components in order to reduce pollutant emissions, improve fuel economy and reduce noise.

The automotive industry is always striving to reduce emissions in the form of pollutants and noise in order to meet constantly increasing requirements, as well as to save mass and space in order to make vehicles more efficient.

The object of the invention is to provide a vehicle exhaust system with particularly efficient soundproofing.

To achieve the object, a vehicle exhaust system is provided with a section close to the engine or upstream, which has a close-coupled exhaust system component that after-treats emissions generated by an engine and/or dampens noise. The vehicle exhaust system further has a remote or downstream portion that includes a remote exhaust system component that attenuates noise and/or that aftertreats emissions generated by an engine, and an exhaust pipe that is downstream of the remote engine exhaust system component and is fluidly connected to the remote exhaust system component. Furthermore, the vehicle exhaust system has an intermediate pipe which fluidically connects the exhaust system component close to the engine to the exhaust system component remote from the engine. The intermediate tube has one or more soundproofing openings in its tube wall. The vehicle exhaust system has an intermediate pipe shell that defines a chamber between itself and the intermediate pipe. The intermediate pipe is connected in terms of flow to the chamber via at least one of the sound-damping openings. Furthermore, the intermediate pipe shell has a ventilation opening, via which the chamber is fluidically connected to the section remote from the engine, i. H. upstream of the end of the vehicle exhaust system where the exhaust gas is discharged to the atmosphere via a tailpipe. For the purpose of the application, the emissions generated by an engine are exhaust gases, in particular exhaust gases containing pollutants. The exhaust gas in the chamber is thus routed separately from the flow in the intermediate pipe to the section remote from the engine via the ventilation opening. If the exhaust system component close to the engine is designed to clean exhaust gas, cleaned exhaust gas in the chamber is routed via the ventilation opening separately from the flow in the intermediate pipe to the section remote from the engine. It was recognized that resonances in the vehicle exhaust system can be suppressed very close to the engine by means of the soundproofing openings in the intermediate pipe. In this way, a vehicle exhaust system can be provided which has particularly effective soundproofing and is of particularly compact design, since further soundproofing components can be made smaller or can be omitted entirely.

The intermediate pipe shell ensures that exhaust gas escaping via the soundproofing openings is caught in the chamber and fed back downstream of the section remote from the engine. In this way, the exhaust gas is defined by the vehicle's exhaust gas line and guided out of it via the tailpipe, as a result of which the emissions are particularly low in pollutants.

The distance between the sound-damping openings and the intermediate pipe casing is dimensioned in such a way that the intermediate pipe casing does not significantly impede the breaking up or suppression of resonances in the intermediate pipe.

The radial distance between the intermediate pipe with the one or more soundproofing openings and the intermediate pipe casing can form an annular gap that is less than 20 mm, preferably less than 10 mm.

In one embodiment, the intermediate pipe is a resonance-free pipe, which is also known by the English term “resonance-free pipe” or the abbreviation “RFP”. The non-resonant tube ensures a particularly effective soundproofing, in particular since the sound-damping openings in the non-resonant tube are arranged at predetermined locations along the length of the non-resonant tube which are particularly effective in reducing resonant frequency noise.

In one embodiment, the intermediate tube has a length of greater than or equal to 500 mm, preferably greater than or equal to 800 mm. With an intermediate tube length of greater than or equal to 500 mm, preferably greater than or equal to 800 mm, the resonant frequencies that occur usually shift to lower resonant frequencies. This increases the risk of unwanted low-frequency humming or booming noises occurring. The resonance frequencies are shifted to higher ranges through the sound-damping openings in the tube wall of the intermediate tube, which results in the suppression of low-frequency noises.

The exhaust system component close to the engine can be a three-way catalytic converter, a catalytic converter with selective catalytic reduction, an oxidation catalytic converter and/or a particle filter.

The exhaust system component remote from the engine can be a three-way catalyst, a selective catalytic reduction catalyst, an oxidation catalyst and/or a particulate filter, which means that the intermediate pipe is particularly close to the engine, i. H. particularly far upstream.

Alternatively, the exhaust system component close to the engine and/or the exhaust system component remote from the engine can be an exhaust gas silencer, a silencer valve, a reflection silencer and/or an active noise reduction system. This has the advantage that the exhaust gas that flows through the intermediate pipe and can therefore escape via the silencing openings has already passed through most of the components, in particular all those, that reduce the emissions produced by the engine. The exhaust gas that is released into the environment via the vehicle exhaust system therefore has a particularly low concentration of pollutants.

It can be provided that the intermediate tube casing completely closes the chamber to the environment, except for the ventilation opening. This ensures that exhaust gas from the chamber cannot escape directly to the environment, but is completely fed via the ventilation opening to the section remote from the engine.

Preferably, the intermediate tube is in fluid communication with the chamber through each of its sound attenuation ports. This means that the intermediate tube shell extends over all soundproofing openings and the exhaust gas escaping via the soundproofing openings is therefore completely caught by the intermediate tube shell or in the chamber. In this way, the entire exhaust gas is routed to the end of the vehicle exhaust system in a defined manner.

In a further embodiment, the vehicle exhaust system has a connecting line, by means of which the chamber is connected in terms of flow via the ventilation opening to the exhaust system component remote from the engine. As a result, the exhaust gas from the chamber is fed to the exhaust system component remote from the engine and can thus be treated in the exhaust system component remote from the engine like the exhaust gas which flows through the intermediate pipe directly into the exhaust system component remote from the engine.

In an alternative embodiment, the vehicle exhaust system has a connecting line, by means of which the chamber is connected in terms of flow via the ventilation opening directly to the exhaust pipe of the section remote from the engine. The connecting line forms a bypass that directs the exhaust gas from the chamber past the exhaust system component remote from the engine. In this way, the back pressure acting in the connecting pipe can be reduced, so that the exhaust gas can be reliably discharged from the chamber via the connecting pipe.

Furthermore, it can be provided that the intermediate pipe sleeve is spaced apart from the exhaust system component remote from the engine. The intermediate pipe sleeve and the exhaust system component remote from the engine are therefore different components and do not adjoin one another.

According to one embodiment, the vent opening is located at a downstream end of the intermediate tube shell. The intermediate tube sleeve ends at the downstream end on the exhaust system component remote from the engine and the chamber is directly fluidically connected to the exhaust system component remote from the engine via the ventilation opening. In this way, the exhaust gas is routed from the chamber via the ventilation opening directly into the exhaust system component remote from the engine, so that no connecting line is required and the vehicle exhaust system can therefore be designed compactly and with little effort. As a result, the exhaust gas from the chamber is fed to the exhaust system component remote from the engine and can thus be treated in it. In this embodiment, the exhaust gas flows out of the chamber separately from the exhaust gas in the intermediate pipe into the exhaust system component remote from the engine, as a result of which the vehicle exhaust system can have particularly favorable flow properties in this area.

According to a further embodiment, the exhaust pipe of the section remote from the engine is a tail pipe and thus forms the end of the vehicle exhaust system, at which the exhaust gas is released into the environment in a targeted manner.

It should be emphasized that more than two exhaust system components can also be provided and that an intermediate pipe with an intermediate pipe sleeve arranged around it can be provided between two exhaust system components that are directly flow-connected.

• - 1 in einer schematischen Darstellung eine erfindungsgemäße Fahrzeugabgasanlage,
• - 2 in einer schematischen Darstellung die Fahrzeugabgasanlage aus 1 gemäß einer ersten Ausführungsform,
• - 3 in einer schematischen Darstellung die Fahrzeugabgasanlage aus 1 gemäß einer zweiten Ausführungsform,
• - 4 in einer schematischen Darstellung die Fahrzeugabgasanlage aus 1 gemäß einer dritten Ausführungsform, und
• - 5 in einer schematischen Darstellung eine erfindungsgemäße Fahrzeugabgasanlage gemäß einer vierten Ausführungsform.

Further advantages and features emerge from the following description and from the accompanying drawings. In these show:

• - 1 in a schematic representation of a vehicle exhaust system according to the invention,
• - 2 the vehicle exhaust system in a schematic representation 1 according to a first embodiment,
• - 3 the vehicle exhaust system in a schematic representation 1 according to a second embodiment,
• - 4 the vehicle exhaust system in a schematic representation 1 according to a third embodiment, and
• - 5 in a schematic representation of a vehicle exhaust system according to the invention according to a fourth embodiment.

In 1 1 is a schematic representation of a vehicle exhaust system 10 as an elongate pipe through which hot exhaust gases generated by an engine 12 are directed for emission reduction and noise reduction.

The vehicle exhaust system 10 has a close coupled portion 14 located immediately downstream of the engine 12 and a close coupled portion 16 located downstream of the close coupled portion 14 .

The long tube is temporarily considered to be closed at one engine end 18 and open at an opposite end 20 where exhaust from the engine 12 exits the vehicle exhaust system 10 to atmosphere after passing through various exhaust system components of the vehicle exhaust system 10 .

• f_n = (nc)/(4L), worin:
• f_n = Resonanzfrequenz der stehenden Welle n (Hz)
• n = Ordnungszahl der stehenden Welle
• c = Schallgeschwindigkeit (m/s)
• L = Länge des geschlossenen-offenen Rohres (m)

sind.Sound waves travel through the tube from their source, which is the engine 12, and then exit to the atmosphere. When the sound wave encounters a limitation of some kind, such as a change in impedance, part of the wave will be reflected back the way it came, and the rest will continue. In a closed-open tube, as in 1 shown, this reflection occurs at the exit of the tube. The reflected wave interferes with the incident wave, and at certain frequencies, which depend on the length of the pipe, they constructively interfere in such a way that the level of the wave increases and this further makes the wave appear stationary. Such waves are called standing waves and, for a closed-open pipe, the frequencies of such waves can be calculated using the equation below.

• f _n = (nc)/(4L), where:
• f _n = resonant frequency of standing wave n (Hz)
• n = atomic number of the standing wave
• c = speed of sound (m/s)
• L = closed-open tube length (m)

are.

The chart of 1 shows the first three standing pressure waves for a closed-open tube. The pressure here is maximum for each standing wave at the closed motor end 18 (antinode) and minimum at the open end 20 to the atmosphere (nodes).

In order to reduce such pressure antinodes or to suppress the occurrence of such resonances and thus to reduce the noise emissions of the vehicle exhaust system 10, the vehicle exhaust system 10 has an intermediate pipe 22 (see 2 ) with soundproofing openings 24.

The sound deadening openings 24 are arranged in the pipe wall at predetermined locations along a length of the intermediate pipe 22 in order to reduce corresponding resonant frequency noises.

The intermediate pipe 22 fluidly connects an exhaust system component 26 close to the engine of the section 14 close to the engine to an exhaust system component 28 remote from the engine of the section 16 remote from the engine and is thus arranged relatively close to the end 18 of the engine.

Close-coupled exhaust system component 26 is an aftertreatment component configured to remove pollutants from the exhaust gas, such as a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a gasoline particulate filter (GPF), a Three-way catalyst (TWC) or a selective catalytic reduction (SCR) catalyst.

Of course, the section 14 close to the engine can have further exhaust system components, in particular after-treatment components for reducing pollutants in the exhaust gas.

In the present exemplary embodiment, the exhaust system component 28 remote from the engine is an aftertreatment component which, like the exhaust system component 26 close to the engine, is set up to remove pollutants from the exhaust gas, for example a diesel oxidation catalyst (DOC (diesel oxidation catalyst)), a diesel particulate filter (DPF), a gasoline particulate filter (GPF (gasoline particulate filter)), a three-way catalyst (TWC) or a selective catalytic reduction (SCR) catalyst.

In an alternate embodiment, the remote exhaust system component 28 is an acoustic aftertreatment component configured to reduce noise emissions, such as an exhaust muffler, a reflective muffler, a muffler valve, or an active noise reduction system.

In principle, the section 16 remote from the engine can have further exhaust system components, in particular acoustic aftertreatment components.

The exhaust system components described can be mounted in different designs and combinations depending on the vehicle application and the available installation space.

In the present embodiment, the intermediate pipe 22 is designed as a resonance-free pipe (RFP) so that no resonances can arise in the intermediate pipe 22 and/or in the vehicle exhaust system 10 that contribute significantly to disruptive noise emissions.

The sound-damping openings 24 are in the form of through-holes, as a result of which the intermediate pipe 22 can be produced with little effort. According to a variant of the invention, the through-holes are micro-perforations, each having a maximum cross-section of 2 mm ² and a degree of perforation (ratio of perforated area/total area) in the hole area of 1 to 3%.

Alternatively, at least a portion of the sound attenuation openings 24 may be covered with a mesh, mesh, or micro-perforated material to further reduce noise.

In principle, the intermediate pipe 22 can be any exhaust pipe with at least one soundproofing opening 24 which is designed to reduce noise emissions.

During operation, exhaust gas generated by the engine 12 flows through the section 14 close to the engine via the exhaust system component 26 close to the engine into the intermediate pipe 22 and from the intermediate pipe 22 via the exhaust system component 28 remote from the engine through an exhaust pipe 30 of the section 16 remote from the engine and finally via an exhaust system outlet 32 at the end 20 into the The atmosphere. In the 2 the flow path of the exhaust gas is illustrated by arrows.

The exhaust pipe 30 may be part of one or more tailpipes of the vehicle exhaust system 10 .

In order to prevent exhaust gases from being discharged directly into the atmosphere via the soundproofing openings 24, the vehicle exhaust system 10 has an intermediate pipe shell 34 which encloses the intermediate pipe 22 in a gas-tight manner.

In this case, a chamber 36 is formed between the intermediate pipe 22 and the intermediate pipe casing 34, into which the sound-damping openings 24 open.

Exhaust gas exiting the intermediate pipe 22 via the muffler openings 24 is thus captured in the chamber 36 . In the illustrated embodiment, the intermediate tube sleeve 34 is in the form of a hollow cylinder with closed axial ends 38, 39, through which the intermediate tube 22 extends in the axial direction.

The intermediate tube shell 34 extends from the upstream end 38 to the downstream end 39 over all of the muffler openings 24 so that all of the exhaust gas exiting through the muffler openings 24 flows into the chamber 36 .

Furthermore, the downstream end 39 is at a distance from the exhaust system component 28 remote from the engine, so that the intermediate pipe sleeve 34 has no contact with the exhaust system component 28 remote from the engine or is not directly connected to it.

In particular, the intermediate pipe sleeve 34 and the exhaust system component 28 remote from the engine are separate components in this case.

In principle, the intermediate pipe sleeve 34 can be of any design and can be connected to the intermediate pipe 22 in any manner and/or enclose any desired section of the outside of the intermediate pipe 22, in particular any number of the soundproofing openings 24. In the latter case, for example, the intermediate pipe sleeve 34 can be designed like a trough and attached to the edge of the intermediate tube 22 and thus enclose the intermediate tube 22 only on one side. The open end of the trough is then closed by intermediate pipe 22.

In all of the embodiments, the intermediate pipe shell 34 has a vent opening 40 through which exhaust gas can be diverted from the chamber 36 into a downstream portion of the vehicle exhaust system 10 with respect to the intermediate pipe 22 .

in the in 2 The embodiment shown is the intermediate tube sleeve 34 via the ventilation opening 40 by means of a connecting line 42 connected to the exhaust pipe 30. Thus, during operation, the exhaust gas flows out of the chamber 36 via the connecting line 42 past the exhaust system component 28 remote from the engine and via the exhaust pipe 30 into the atmosphere. The connecting line 42 thus forms a bypass for the exhaust system component 28 remote from the engine.

The ventilation opening 40 is here arranged on a lateral surface of the intermediate tube sleeve 34 which is spaced from the axial ends 38, 39.

The proportion of exhaust gas that flows through the silencer openings 24 into the chamber 36 and thus bypasses the remote exhaust system component 28 via the bypass is small compared to the proportion of exhaust gas that flows from the intermediate pipe 22 through the remote exhaust system component 28 . Thus, the pollutant concentration of the exhaust gas released into the atmosphere does not increase significantly through the bypass, even if the remote exhaust system component 28 is configured to remove pollutants from the exhaust gas.

Based on 3 A vehicle exhaust system 10 according to a second embodiment will now be described. The same reference numerals are used for the components that are known from the above embodiment, and reference is made to the preceding explanations.

In contrast to the first embodiment, in which the connecting line 42 forms a bypass, the connecting line 42 in the second embodiment ends in the exhaust system component 28 remote from the engine. Thus, during operation, the exhaust gas flows out of the chamber 36 via the connecting line 42 into the exhaust system component 28 remote from the engine and from there via the exhaust pipe 30 into the atmosphere.

Based on 4 A vehicle exhaust system 10 according to a third embodiment will now be described. The same reference numerals are used for the components that are known from the above embodiment, and reference is made to the preceding explanations.

In contrast to the previous embodiments, the vehicle exhaust system 10 in the third embodiment has no connecting line 42 .

Furthermore, the intermediate pipe shell 34 extends to the engine-distal exhaust system component 28 so that the intermediate pipe shell 34 at the downstream end 39 is adjacent to the engine-distal exhaust system component 28 and is attached to it.

The ventilation opening 40 is arranged in the downstream end 39 and forms a connection via which the exhaust gas can flow from the chamber 36 directly into the exhaust system component 28 remote from the engine.

In particular, during operation the exhaust gas in the chamber 36 does not flow via the intermediate pipe 22, but rather parallel and thus separately from the gas in the intermediate pipe 22 into the exhaust system component 28 remote from the engine.

In this manner, a vehicle exhaust system 10 is provided which has sound deadening openings 24 at locations which are located very far upstream from the end 20 and which provide particularly effective noise deadening.

The intermediate pipe sleeve 34 ensures that exhaust gas escaping via the soundproofing openings 24 is caught and released to the environment in a defined manner via the exhaust system outlet 32 .

Furthermore, the intermediate tube sleeve 34 protects the soundproofing openings 24 from environmental influences, for example from stone chips or mud, which could damage or clog the soundproofing openings 24 .

5 shows that more than two exhaust system components can be provided. Between the exhaust system components 26 and 28 there is another exhaust system component 27, which can be, for example, an exhaust muffler, a silencing valve, a reflective muffler and/or an active noise reduction system.

One or one intermediate pipe 22, together with the intermediate pipe sleeve 34, can be provided between the exhaust gas components 26 and 27 and/or between the exhaust gas components 27 and 28, as has already been described several times above, with the exhaust system component 27 being an exhaust system component remote from the engine in the first case and a component close to the engine in the second case exhaust system component.

The combinations of which exhaust gas components 26, 27 and 28 fulfill which function (exhaust gas cleaning function or silencing function) are not restrictive.

The intermediate tube or tubes 22 have a length of greater than or equal to 500 mm, preferably greater than or equal to 800 mm.

The invention is not limited to the embodiments shown. In particular, can individual features of an embodiment can be combined with features of other embodiments, in particular independently of the other features of the corresponding embodiments.

Claims (10)

Vehicle exhaust system with a section (14) close to the engine, which has an exhaust system component (26) close to the engine, which after-treats emissions generated by an engine (12) and/or dampens noise, a section (16) remote from the engine, which has an exhaust system component (28) remote from the engine, which Muffles noise and/or post-treats emissions generated by an engine (12), and has an exhaust pipe (30) which is arranged downstream of the exhaust system component (28) remote from the engine and is fluidically connected to the exhaust system component (28) remote from the engine, and an intermediate pipe (22 ) which fluidly connects the exhaust system component (26) close to the engine with the exhaust system component (28) remote from the engine, characterized in that the intermediate pipe (22) has one or more soundproofing openings (24) in its pipe wall, the vehicle exhaust system (10) having an intermediate pipe casing (34 ) defining a chamber (36) between itself and the intermediate tube (22), the intermediate tube (22) being in fluid communication with the chamber (36) via at least one of the sound attenuation openings (24), and the intermediate tube envelope (34) has a ventilation opening (40) via which the chamber (36) is fluidically connected to the section (16) remote from the motor. vehicle exhaust system claim 1 , characterized in that the intermediate tube (22) is a resonance-free tube. vehicle exhaust system claim 1 or 2 , characterized in that the intermediate tube (22) has a length of greater than or equal to 500 mm, preferably greater than or equal to 800 mm. Vehicle exhaust system according to one of the preceding claims, characterized in that the exhaust system component (26) close to the engine and/or the exhaust system component (28) remote from the engine is a three-way catalytic converter, a catalytic converter with selective catalytic reduction, an oxidation catalytic converter and/or a particle filter, or the exhaust system component close to the engine ( 26) and/or the exhaust system component (28) remote from the engine is an exhaust muffler, a muffler valve, a reflective muffler and/or an active noise reduction system. Vehicle exhaust system according to one of the preceding claims, characterized in that the intermediate pipe casing (34) completely closes the chamber (36) to the environment, apart from the ventilation opening (40). Vehicle exhaust system according to one of the preceding claims, characterized in that the intermediate pipe (22) is fluidically connected to the chamber (36) via each of its sound-damping openings (24). Vehicle exhaust system according to one of the preceding claims, characterized in that the vehicle exhaust system (10) has a connecting line (42) by means of which the chamber (36) connects via the ventilation opening (40) to the exhaust system component (28) remote from the engine or directly to the exhaust pipe (30 ) is fluidly connected. Vehicle exhaust system according to one of the preceding claims, characterized in that the intermediate pipe sleeve (34) is at a distance from the exhaust system component (28) remote from the engine. Vehicle exhaust system according to one of Claims 1 until 6 , characterized in that the ventilation opening (40) is arranged at a downstream end (39) of the intermediate pipe shell (34), the intermediate pipe shell (34) ending at the downstream end (39) on the exhaust system component (28) remote from the engine and the chamber ( 36) via the ventilation opening (40) is directly connected in terms of flow to the exhaust system component (28) remote from the engine. Vehicle exhaust system according to one of the preceding claims, characterized in that the exhaust pipe (30) is a tail pipe.

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