U.S. patent application number 16/642460 was filed with the patent office on 2020-08-13 for exhaust system as well as motor vehicle with an exhaust system.
The applicant listed for this patent is Faurecia Emissions Control Technologies, Germany GmbH. Invention is credited to Marianne BOUDOY, Aurelie Demont, M. Romaine Joly, Stephane Nezan, Hannes STEINKILBERG.
Application Number | 20200256227 16/642460 |
Document ID | 20200256227 / US20200256227 |
Family ID | 1000004826280 |
Filed Date | 2020-08-13 |
Patent Application | download [pdf] |
United States Patent
Application |
20200256227 |
Kind Code |
A1 |
STEINKILBERG; Hannes ; et
al. |
August 13, 2020 |
EXHAUST SYSTEM AS WELL AS MOTOR VEHICLE WITH AN EXHAUST SYSTEM
Abstract
An exhaust system for an internal combustion engine of a motor
vehicle includes a single exhaust-gas inlet line, two exhaust-gas
outlet lines connected in an exhaust gas-conducting manner to the
exhaust-gas inlet line, and an active silencing device. The active
silencing device is connected in a sound-conducting manner to the
two exhaust-gas outlet lines. Furthermore, a motor vehicle with
such an exhaust system is provided.
Inventors: |
STEINKILBERG; Hannes;
(Augsburg, DE) ; BOUDOY; Marianne; (Montbeliard,
FR) ; Joly; M. Romaine; (Arcey, FR) ; Demont;
Aurelie; (Montenois, FR) ; Nezan; Stephane;
(Etupes, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Faurecia Emissions Control Technologies, Germany GmbH |
Augsburg |
|
DE |
|
|
Family ID: |
1000004826280 |
Appl. No.: |
16/642460 |
Filed: |
August 31, 2017 |
PCT Filed: |
August 31, 2017 |
PCT NO: |
PCT/EP2017/071894 |
371 Date: |
February 27, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 2470/18 20130101;
F01N 2470/14 20130101; F01N 2470/02 20130101; F01N 1/04
20130101 |
International
Class: |
F01N 1/04 20060101
F01N001/04 |
Claims
1. An exhaust system for an internal combustion engine of a motor
vehicle comprising: a single exhaust-gas inlet line; two
exhaust-gas outlet lines connected in an exhaust gas-conducting
manner to the single exhaust-gas inlet line; and an active
silencing device, which is connected in a sound-conducting manner
to the two exhaust-gas outlet lines.
2. The exhaust system according to claim 1, wherein the single
exhaust-gas inlet line is connected in an exhaust gas-conducting
manner to the two exhaust-gas outlet lines via a passive
silencer.
3. The exhaust system according to claim 2, wherein sections of the
single exhaust-gas inlet line and/or of at least one of the two
exhaust-gas outlet lines, run inside a silencer housing of the
passive silencer.
4. The exhaust system according to claim 1, wherein the two
exhaust-gas outlet lines form a T connection or a Y connection with
the single exhaust-gas inlet line or an intermediate exhaust-gas
line, wherein the intermediate exhaust-gas line is connected in an
exhaust gas-conducting manner to both of the two exhaust-gas outlet
lines and to the single exhaust-gas inlet line.
5. The exhaust system according to claim 1, wherein the two
exhaust-gas outlet lines are formed by opposite sections of a
common exhaust-gas outlet pipe.
6. The exhaust system according to claim 1, wherein the active
silencing device is connected in a sound-conducting manner to the
two exhaust-gas outlet lines via a sound coupling-in line, wherein
the sound coupling-in line surrounds exhaust-gas inlet-facing ends
of the two exhaust-gas outlet lines on an outside and runs
substantially concentric to the exhaust-gas inlet-facing ends of
the two exhaust-gas outlet lines.
7. The exhaust system according to claim 6, wherein the single
exhaust-gas inlet line is connected in an exhaust gas-conducting
manner to the two exhaust-gas outlet lines via a passive silencer,
and wherein the sound coupling-in line runs at least partly inside
a silencer housing of the passive silencer.
8. The exhaust system according to claim 6, wherein the single
exhaust gas inlet line passes through a wall of the sound
coupling-in line, or wherein an intermediate exhaust-gas line is
connected in an exhaust gas-conducting manner to both of the two
exhaust-gas outlet lines and to the single exhaust-gas inlet line,
and wherein the intermediate exhaust-gas line passes through a wall
of the sound coupling-in line.
9. The exhaust system according to claim 6, wherein at least one of
the two exhaust-gas outlet lines, comprises a perforated section in
an area surrounded by the sound coupling-in line.
10. The exhaust system according to claim 9, wherein both of the
two exhaust-gas outlet lines comprise perforated sections and the
perforated sections are arranged on opposite sides of the single
exhaust-gas inlet line, or wherein an intermediate exhaust-gas line
is connected in an exhaust gas-conducting manner to both of the two
exhaust-gas outlet lines and to the single exhaust-gas inlet line,
and wherein both of the two exhaust-gas outlet lines comprise
perforated sections and the perforated sections are arranged on
opposite sides of the intermediate exhaust-gas line.
11. The exhaust system according to claim 6, wherein the active
silencing device is connected in a sound-conducting manner to the
sound coupling-in line via a sound line.
12. The exhaust system according to claim 11, wherein the single
exhaust-gas inlet line is connected in an exhaust gas-conducting
manner to the two exhaust-gas outlet lines via a passive silencer,
and wherein the sound line runs outside a silencer housing of the
passive silencer.
13. The exhaust system according to claim 1, wherein the two
exhaust-gas outlet lines are exhaust tail pipes.
14. The exhaust system according to claim 1, wherein the singe
exhaust-gas inlet line has a substantially oval cross section at an
exhaust-gas outlet-facing end.
15. A motor vehicle including the exhaust system according to claim
1.
16. The exhaust system according to claim 2, wherein sections of
the single exhaust-gas inlet line, and/or both of the two
exhaust-gas outlet lines, run inside a silencer housing of the
passive silencer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US national phase of
PCT/EP2017/071894, filed 2017 Aug. 31.
BACKGROUND
[0002] The invention relates to an exhaust system for an internal
combustion engine of a motor vehicle.
[0003] In addition, the invention relates to a motor vehicle with
an exhaust system.
[0004] Exhaust systems with one or more tail pipes are known from
the state of the art, wherein a plurality of tail pipes are used
when relatively large flow cross sections are to be provided for
one exhaust gas flow. The external appearance of an associated
motor vehicle can also be designed by means of the number of tail
pipes. In this context, particularly sporty motor vehicles often
have two or more tail pipes, for example.
[0005] Exhaust systems with more than one exhaust tail pipe are
also referred to as multi-flow.
[0006] Moreover, it is known from the state of the art to equip
exhaust systems with active silencing devices in order to muffle
noises emitted by the exhaust system to the surroundings, or
ideally to eliminate them completely.
[0007] For this, the active silencing devices usually comprise a
loudspeaker, with the aid of which they generate sound which is
superimposed on the sound carried by the exhaust gas flow. The
superposition is ideally effected destructively, i.e. it is sought
to superimpose the sound generated by the loudspeaker out of phase
on the sound carried by the exhaust gas flow.
[0008] Multi-flow exhaust systems which are equipped with active
silencing devices are known, for example, from DE 100 85 230 B3, EP
2 915 967 A1 and DE 10 2012 200 712 A1. Each exhaust gas tract is
allocated an active silencing device. As a result, such exhaust
systems have a complex construction with respect to the silencing
devices and are thus relatively expensive.
[0009] In addition, multi-flow exhaust systems are known, which
have several exhaust-gas inlet lines. Such exhaust systems
therefore have several exhaust gas inlets and several exhaust gas
outlets. Such exhaust systems are used in particular in connection
with internal combustion engines, the cylinders of which are
arranged in a V formation. Then, one exhaust-gas inlet line is
connected in an exhaust gas-routing manner to the cylinders of a
first cylinder bank and another exhaust-gas inlet line is connected
in an exhaust gas-routing manner to the cylinders of a second
cylinder bank. Such exhaust systems can also be equipped with a
silencing device, as can be learned from EP 2 818 654 A1 or EP 0
481 450 A1, for example. Here, the active silencing devices act on
the exhaust gas routed in both tail pipes. Such exhaust systems
have a complex construction in particular because of the two
exhaust-gas inlet lines. In addition, they are not very suitable
for use in connection with in-line engines.
SUMMARY
[0010] The subject disclosure provides an improved exhaust system
which is multi-flow with respect to the exhaust gas outlets and
comprises an active silencing device. The exhaust system should be
as simple in construction and in production as possible. In
addition, an effective muffling of the sound emitted via the
exhaust gas flow to the surroundings should be guaranteed for all
tail pipes. Furthermore, a motor vehicle with such an exhaust
system is intended to be specified.
[0011] In one exemplary embodiment, an exhaust system comprises a
single exhaust-gas inlet line, two exhaust-gas outlet lines
connected in an exhaust gas-conducting manner to the exhaust-gas
inlet line, and an active silencing device which is connected in a
sound-conducting manner to the two exhaust-gas outlet lines. The
exhaust-gas inlet line is connected in an exhaust gas-conducting
manner to the cylinders of the internal combustion engine. Between
the internal combustion engine and the exhaust-gas inlet line,
further exhaust system elements can be arranged which serve, for
example, for cleaning the exhaust gas. The exhaust-gas outlet lines
are formed to conduct exhaust gas to the surroundings of the
exhaust system. They can also be referred to as exhaust tail pipes.
The exemplary exhaust system therefore combines a single
exhaust-gas inlet line and a single silencing device with two
exhaust-gas outlet lines. The exhaust system thus has a
particularly simple construction. In particular, in comparison with
the state of the art, a second exhaust-gas inlet line and/or a
second active silencing device can be dispensed with. The
sound-conducting connection of the silencing device to the two
exhaust-gas outlet lines additionally guarantees effective
silencing.
[0012] According to one embodiment, the silencing device can also
be formed as a so-called sound actuator, in which the sound design
is an important aspect (alternatively or in addition to the
silencing).
[0013] The active silencing device can comprise a sound-generating
device, in particular a loudspeaker, which is arranged in a
sound-generating device housing. The sound-generating device per se
therefore has a construction already known and proven from the
state of the art. It is thus robust and reliable. Furthermore, it
can be cost-effectively produced or obtained in the market.
[0014] According to a variant, the exhaust-gas inlet line is
connected in an exhaust gas-conducting manner to the exhaust-gas
outlet lines via a passive silencer. The passive silencer can be a
rear silencer. The passive silencer serves to reduce the sound
emitted to the surroundings. The passive silencer and the active
silencing device therefore serve the same purpose. The active
silencing device and the passive silencer can be matched to each
other. This can be effected, for example, in that the passive
silencer is designed to muffle relatively low frequencies and the
active silencing device is designed to muffle relatively high
frequencies. In summary, a particularly good muffling of the sound
emitted to the environment by the exhaust system is guaranteed by
the passive silencer.
[0015] The passive silencer preferably comprises a silencer
housing.
[0016] Sections of the exhaust-gas inlet line and/or of at least
one of the exhaust-gas outlet lines, preferably of both exhaust-gas
outlet lines, can run inside a silencer housing of the passive
silencer. The exhaust-gas inlet line thus passes through a section
of the wall of the silencer housing. Observed from inside the
silencer housing, the exhaust-gas inlet line therefore protrudes
from a section of the wall of the silencer housing. The protruding
section of the exhaust-gas inlet line, therefore the section of the
exhaust-gas inlet line running inside the silencer housing, can
comprise cross-section changes and/or changes of orientation, for
example in the form of curvatures. The same applies to the at least
one exhaust-gas outlet line or both exhaust-gas outlet lines. The
cross-section changes and/or changes of orientation of the
exhaust-gas inlet line and/or the exhaust-gas outlet lines can be
chosen such that an improved muffling effect is achieved by the
passive silencer. The sound emitted to the surroundings of the
exhaust system is thus muffled particularly effectively.
[0017] In another variant in which the active sound-generating
device is designed in such a way that it completely or almost
completely eliminates the sound emitted by the exhaust system to
the environment, a passive silencer can be dispensed with. By the
complete elimination, it is meant here that the emitted sound is
muffled in such a way that a predetermined threshold value is not
exceeded. Such an exhaust system has a particularly simple and
space-saving construction.
[0018] In an embodiment, the two exhaust-gas outlet lines form a T
connection or a Y connection with the exhaust-gas inlet line or an
intermediate exhaust-gas line, wherein the intermediate exhaust-gas
line is connected in an exhaust gas-conducting manner to both
exhaust-gas outlet lines and the exhaust-gas inlet line. In the
case where the exhaust system does not comprise a passive silencer,
the exhaust-gas outlet lines preferably form a T or Y connection
with the exhaust-gas inlet line. If a passive silencer is used, the
exhaust-gas outlet lines preferably form a T or Y connection with
the intermediate exhaust-gas line. The intermediate exhaust-gas
line preferably runs completely inside a silencer housing of the
passive silencer and is thus connected in an exhaust gas-conducting
manner to the exhaust-gas inlet line via an internal volume of the
passive silencer. The T or Y connection is preferably implemented
by welding or soldering of the exhaust-gas lines forming the T or Y
connection, which are realized, for example, in the form of exhaust
gas-conducting pipes. A simple and cost-effective construction of
the exhaust system is thus ensured.
[0019] Both the T and the Y connection is a connection of three
pipe sections. They differ in the angles, which the pipe sections,
more precisely the center axes thereof, assume relative to each
other. Whereas in the case of a T connection two of the pipe
sections substantially have a common center axis and the third pipe
section is oriented substantially perpendicular to this center
axis, the term Y connection covers all connections of three pipe
sections which cannot be referred to as a T connection.
[0020] According to a development, the two exhaust-gas outlet lines
are formed by opposite sections of a common exhaust-gas outlet
pipe. In other words, the exhaust-gas outlet pipe forms a T or Y
connection with the exhaust-gas inlet line or the intermediate
exhaust-gas line in a central section. This T or Y connection
divides the exhaust-gas outlet pipe into two sections lying on
opposite sides of the T or Y connection, which each represent an
exhaust-gas outlet line. In the production of the exhaust system,
only two pipes therefore need to be connected to each other, namely
the pipe forming the exhaust-gas inlet line or the intermediate
exhaust-gas line and the common exhaust-gas outlet pipe. The
production of the exhaust system is thus particularly simple.
[0021] The active silencing device can be connected in a
sound-conducting manner to the exhaust-gas outlet lines via a sound
coupling-in line, wherein the sound coupling-in line surrounds the
exhaust-gas inlet-facing ends of the exhaust-gas outlet lines on
the outside and runs substantially concentric to the exhaust-gas
inlet-facing ends of the exhaust-gas outlet lines. In the case
where the exhaust-gas outlet lines are formed by a common
exhaust-gas outlet pipe, the sound coupling-in line surrounds a
central section of the common exhaust-gas outlet pipe on the
outside and is substantially concentric to it. Therefore, a
diameter of the sound coupling-in line is always greater in that
area in which it surrounds the exhaust-gas inlet-facing ends of the
exhaust-gas outlet lines or the common exhaust-gas outlet pipe on
the outside than a diameter of the common exhaust-gas outlet pipe
or the exhaust-gas inlet-facing ends of the exhaust-gas outlet
lines. The axial ends of the sound coupling-in line thus form
annular openings together with the exhaust-gas outlet lines or the
common exhaust-gas outlet pipe. These are preferably closed. Such a
coupling is often referred to as a Sourdine connection. This
results in a simple but effective way of coupling sound emerging
from the active silencing device into the exhaust-gas outlet
lines.
[0022] The sound coupling-in line can run at least partly inside a
silencer housing of the passive silencer. The sound coupling-in
line preferably runs partly inside the silencer housing and partly
outside it. The exhaust system thereby requires only a small
installation space.
[0023] Moreover, the intermediate exhaust-gas line or the
exhaust-gas inlet line can pass through a wall of the sound
coupling-in line. The result of this is that the T or Y connection
between the intermediate exhaust-gas line or the exhaust-gas inlet
line and the two exhaust-gas outlet lines lies inside the sound
coupling-in line. This also results in a compact construction of
the exhaust system.
[0024] According to an embodiment, at least one of the exhaust-gas
outlet lines, preferably both exhaust-gas outlet lines, comprises a
perforated section in the area surrounded by the sound coupling-in
line. Sound from the sound coupling-in line can pass into the
interior of the exhaust-gas outlet line via the openings forming
the perforation of the perforated section. The sound generated by
the active silencing unit can thus interact with the exhaust gas
routed in the exhaust-gas outlet line and muffle or completely
eliminate sound carried by the exhaust gas flow. When both
exhaust-gas outlet lines comprise perforated sections, these can be
designed differently for example with respect to the number, size
and arrangement of the openings forming the perforation. The
perforation can thus be designed such that a maximum muffling
effect is achieved with respect to the sound emitted by the exhaust
system.
[0025] Advantageously, both exhaust-gas outlet lines comprise
perforated sections and the perforated sections are arranged on
opposite sides of the intermediate exhaust-gas line or on opposite
sides of the exhaust-gas inlet line. The perforated sections
therefore also lie on opposite sides of the T or Y connection. A
compact construction of the exhaust system is thus achieved.
[0026] The active silencing device is preferably connected in a
sound-conducting manner to the sound coupling-in line via a sound
line. The active silencing device is thus arranged at a distance
from the sound coupling-in line, which can substantially correspond
to a length of the sound line. The active silencing device is
thereby also spaced apart from the exhaust gas-routing components
of the exhaust system. The result of this is that the components of
the active silencing device can always be operated at a
temperature, which lies significantly below the temperature of the
exhaust gases routed in the exhaust system. A particularly reliable
and durable functioning of the active silencing device is thereby
ensured.
[0027] The sound line can run outside a silencer housing of the
passive silencer. The sound line is therefore also coupled to the
sound coupling-in line outside the silencer housing. A good
compromise can thereby be achieved between a compact construction
of the exhaust system and a sufficiently large distance between the
active silencing device and the exhaust gas-routing components.
[0028] The exhaust-gas outlet lines are preferably exhaust tail
pipes. The exhaust-gas outlet lines therefore lead directly into
the surroundings of the exhaust system. Exhaust flaps can
optionally be provided in the exhaust-gas outlet lines in order to
close the exhaust-gas outlet lines selectively.
[0029] The exhaust-gas inlet line can have a substantially oval
cross section at an exhaust-gas outlet-facing end. A compact
construction of the exhaust system can be achieved via a cross
section designed in such a way.
[0030] Furthermore, in another exemplary embodiment, a motor
vehicle is provided with an exhaust system as described above. Such
a motor vehicle likewise has a simple construction due to the
simple construction of the exhaust system. In addition, such a
motor vehicle emits only relatively little sound to its
surroundings via its exhaust system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Various embodiment examples are shown in the attached
drawings.
[0032] FIG. 1 schematically shows a motor vehicle with an exhaust
system according to a first embodiment,
[0033] FIG. 2 shows the exhaust system of FIG. 1,
[0034] FIG. 3 shows a section of the exhaust system from FIG. 2,
wherein a portion is represented transparently,
[0035] FIG. 4 schematically shows a detail of the exhaust system
according to FIGS. 1 to 3, and
[0036] FIG. 5 schematically shows an exhaust system according to a
second embodiment.
DETAILED DESCRIPTION
[0037] FIG. 1 shows a motor vehicle 10 with an exhaust system 12
according to a first embodiment, which is coupled to an internal
combustion engine 14 which has three cylinders arranged in a
row.
[0038] As can also be seen in particular in FIG. 2, the exhaust
system 12 comprises a single exhaust-gas inlet line 16 and two
exhaust-gas outlet lines 18 connected in an exhaust gas-conducting
manner thereto, which are exhaust tail pipes in the embodiment
represented.
[0039] In addition, the exhaust system 12 has an active silencing
device 20 which is connected in a sound-conducting manner to the
two exhaust-gas outlet lines 18.
[0040] An active silencing device known from the state of the art,
which comprises a loudspeaker with which it can generate sound
which is out of phase with the sound carried by the exhaust gas
flow, is used as active silencing device 20.
[0041] For this purpose, the active silencing device 20 is coupled
to the exhaust-gas outlet lines 18 via a sound line 22 and a sound
coupling-in line 24.
[0042] In other words, the active silencing device 20 is connected
in a sound-conducting manner to the sound coupling-in line 24 via
the sound line 22.
[0043] The sound coupling-in line 24 in turn is connected in a
sound-conducting manner to the exhaust-gas outlet lines 18.
[0044] The exhaust system 12 further has a passive silencer 26 with
a silencer housing 28.
[0045] In the first embodiment, the exhaust-gas inlet line 16 is
connected in an exhaust gas-conducting manner to the exhaust-gas
outlet lines 18 via the passive silencer 26.
[0046] In FIG. 3, an upper side of the silencer housing 28 is
represented transparent with the result that the interior thereof
can be seen.
[0047] Here, sections of the exhaust-gas inlet line 16 and of both
exhaust-gas outlet lines 18 run inside the silencer housing 28.
[0048] More precisely, a section of the exhaust-gas inlet line 16
facing away from the internal combustion engine 14, thus the
exhaust-gas outlet-facing end thereof, runs inside the silencer
housing 28.
[0049] The exhaust-gas outlet-facing end can have a substantially
oval cross section.
[0050] In this context, the cross section is usually chosen such
that both a good muffling performance of the passive silencer 26
and a compact construction of the exhaust system 12 as a whole are
achieved.
[0051] With regard to the exhaust-gas outlet lines 18, the sections
facing the internal combustion engine 14 or the exhaust-gas inlet
line 16 respectively thus run inside the silencer housing 28.
[0052] In addition, the two exhaust-gas outlet lines 18 form a T
connection 32 with an intermediate exhaust-gas line 30. Both
exhaust-gas outlet lines 18 are thus connected in an exhaust
gas-conducting manner to the intermediate exhaust-gas line 30.
[0053] The T connection 32 lies completely inside the silencer
housing 28.
[0054] In addition, the intermediate exhaust-gas line 30 is
connected in an exhaust gas-conducting manner to the exhaust-gas
inlet line 16 via the internal volume of the passive silencer
26.
[0055] In the first embodiment, the two exhaust-gas outlet lines 18
are formed by opposite sections of a common exhaust-gas outlet pipe
34.
[0056] As already mentioned, the active silencing device 20 is
connected in a sound-conducting manner to the exhaust-gas outlet
lines 18 via the sound coupling-in line 24, in the present case
therefore also to the exhaust-gas outlet pipe 34.
[0057] Here, the sound coupling-in line 24 has a larger diameter
than the exhaust-gas outlet lines 18 and surrounds the exhaust-gas
inlet-facing ends of the exhaust-gas outlet lines 18 on the outside
(see FIG. 4 in particular). In the present case, the sound
coupling-in line 24 therefore also surrounds the exhaust-gas outlet
pipe 34.
[0058] At the same time, the sound coupling-in line 24 runs
substantially concentric to the exhaust-gas outlet lines 18 which
are of course formed by a common exhaust-gas outlet pipe 34.
[0059] The sound coupling-in line 24 runs partly inside the
silencer housing 28 and partly outside it (cf. FIG. 4).
[0060] In order to enable an interaction between the out-of-phase
sound generated by the active silencing unit 20 and the exhaust gas
flow routed in the exhaust-gas outlet lines 18, both exhaust-gas
outlet lines 18 have a perforated section 36.
[0061] In order to illustrate that the two perforated sections 36
can be designed the same but do not have to be, they differ in FIG.
4 with respect to the number of openings belonging to the
perforated section 36 as well as the arrangement of the
openings.
[0062] The perforated sections 36 are arranged in that area of the
exhaust-gas outlet lines 18 which is surrounded by the sound
coupling-in line 24.
[0063] Furthermore, the perforated sections 36 are placed on
opposite sides of the intermediate exhaust-gas line 30.
[0064] The intermediate exhaust-gas line 30 passes through a wall
of the sound coupling-in line 24. The T connection 32 thus lies
inside the sound coupling-in line 24.
[0065] The sound line 22 runs completely outside the silencer
housing 28.
[0066] In summary, exhaust gas emerging from the internal
combustion engine 14 therefore flows via the exhaust-gas inlet line
16 into the silencer housing 28 of the passive silencer 26. From
there, it passes via the intermediate exhaust-gas line 30, which is
coupled to the two exhaust-gas outlet lines 18 via the T connection
32, into the two exhaust-gas outlet lines 18. These conduct the
exhaust gas to the surroundings.
[0067] Within the meaning of muffling the sound carried by the
exhaust gas, out-of-phase sound, which is often also referred to as
anti-noise, is generated in the active silencing device 20. From
there, the out-of-phase sound is routed into the sound coupling-in
line 24 via the sound line 22. It thus passes into an annular
space, which is formed by the sound coupling-in line 24 and the
respectively exhaust-gas inlet-facing ends of the exhaust-gas
outlet lines 18. From this, the sound can escape via the openings
of the perforated sections 36 into the interior of the exhaust-gas
outlet lines 18, where it interacts with the sound carried by the
exhaust gas in order to muffle it.
[0068] In contrast to the first embodiment, the second embodiment
of the exhaust system 12 shown in FIG. 5 dispenses with the passive
silencer 26.
[0069] This variant can be chosen when the exhaust system 12 is to
be designed in a particularly space-saving manner.
[0070] This variant can also be used when the active silencing
device 20 is designed in such a way that it can ensure sufficient
muffling of the sound carried by the exhaust gas without the aid of
a passive silencer.
[0071] In addition, in the second embodiment no intermediate
exhaust-gas line 30 is used with the result that the exhaust-gas
inlet line 16 forms the T connection 32 with the exhaust-gas outlet
lines 18. The exhaust gas therefore flows directly from the
exhaust-gas inlet line 16 into the exhaust-gas outlet lines 18.
[0072] The path of the out-of-phase sound generated by the active
silencing device 20 and its superposition with the sound carried by
the exhaust gas is effected in the same way as in the first
embodiment. Reference is therefore made to the above
statements.
[0073] Here, the perforated sections 36 are again designed
differently. This serves to illustrate that they can be made the
same but do not have to be.
[0074] Although various embodiments have been disclosed, a worker
of ordinary skill in this art would recognize that certain
modifications would come within the scope of this disclosure. For
that reason, the following claims should be studied to determine
the true scope and content of this disclosure.
* * * * *