EXHAUST SYSTEM FOR AN INTERNAL COMBUSTION ENGINE OF A MOTOR VEHICLE AS WELL AS MOTOR VEHICLE

Abstract

An exhaust system for an internal combustion engine of a motor vehicle includes an exhaust-gas line and an associated active silencing device. A sound coupling-in line of the silencing device substantially concentrically surrounds the exhaust-gas line on the outside. A first perforation is provided in an axial portion facing away from a sound line in an area of the exhaust-gas line enclosed by the sound coupling-in line. An axial portion facing the sound line is designed perforation-free at least in a portion. Furthermore, a motor vehicle with such an exhaust system is explained.

Claims

1. An exhaust system for an internal combustion engine of a motor vehicle comprising: an exhaust-gas line routing exhaust gas; an active silencing device that comprises a sound-generating unit which is acoustically coupled to the exhaust-gas line via a sound line and a sound coupling-in line connected downstream thereto, such that sound generated by the sound-generating unit can be introduced into an exhaust gas flow present inside the exhaust-gas line; wherein the sound coupling-in line substantially concentrically surrounds the exhaust-gas line on an outside and an area of the exhaust-gas line enclosed by the sound coupling-in line has an axial portion facing the sound line and an axial portion connected downstream thereto facing away from the sound line; and wherein a first perforation is provided in the axial portion facing away from the sound line and the axial portion facing the sound line is designed perforation-free at least in a portion.

2. The exhaust system of claim 1 wherein the first perforation runs around a whole periphery of the axial portion of the exhaust-gas line facing away from the sound line.

3. The exhaust system of claim 1 wherein openings comprised by the first perforation each have a substantially round cross section.

4. The exhaust system of claim 1 wherein, in the area enclosed by the sound coupling-in line upstream of the first perforation, the exhaust-gas line has a second perforation in a peripheral portion facing away from the sound line, wherein a peripheral portion facing the sound line is designed perforation-free.

5. The exhaust system of claim 4 wherein at least one radial rib is provided on an outer surface of the exhaust-gas line between the peripheral portion facing away from the sound line and the peripheral portion facing the sound line.

6. The exhaust system of claim 4 wherein at least one radial rib is provided on an inner surface of the sound coupling-in line between the peripheral portion facing away from the sound line and the peripheral portion facing the sound line.

7. The exhaust system of claim 5 wherein the at least one radial rib comprises a plurality of ribs with one radial rib being provided in each of two border areas between the peripheral portion facing away from the sound line and the peripheral portion facing the sound line.

8. The exhaust system of claim 5 wherein the at least one radial rib is shorter in an axial direction of the exhaust-gas line than the sound coupling-in line.

9. The exhaust system of claim 4 wherein openings comprised by the second perforation each have a substantially rectangular cross section.

10. The exhaust system of claim 5 wherein a radial outer end of the at least one radial rib or radial ribs provided on the outer surface of the exhaust-gas line is or are at a radial distance from the sound coupling-in line, wherein each radial rib radiating from the exhaust-gas line is complemented by a radial rib, pointing radially inwards radiating from the sound coupling-in line, which is at only a small peripheral distance from an associated radial rib radiating from the exhaust-gas line or touches the periphery of same, and the radial inside end of which is at a radial distance from the exhaust-gas line.

11. The exhaust system of claim 1 wherein, in an area upstream of the sound coupling-in line, the exhaust-gas line has an axial bend or an axial kink.

12. The exhaust system of claim 11 wherein, in the area enclosed by the sound coupling-in line upstream of the first perforation, the exhaust-gas line has a second perforation in a peripheral portion facing away from the sound line, wherein a peripheral portion facing the sound line is designed perforation-free, and wherein the second perforation is arranged downstream of a convex area of the axial bend or of the axial kink.

13. The exhaust system of claim 1 wherein a center axis of the sound line runs substantially along a radial direction of the sound coupling-in line.

14. The exhaust system of claim 5 wherein the at least one radial rib extends up to the sound coupling-in line.

15. The exhaust system of claim 6 wherein the at least one radial rib extends up to the sound coupling-in line.

16. The exhaust system of claim 9 wherein a short side of the rectangle is oriented in a peripheral direction and a long side of the rectangle is oriented in an axial direction of the exhaust-gas line.

17. The exhaust system of claim 11 wherein the axial bend or axial kink is substantially 90.

18. A motor vehicle with an exhaust system of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure is explained below with reference to various embodiment examples which are shown in the attached drawings. There are shown in:

[0029] FIG. 1 shows a schematic view of a motor vehicle according to the disclosure with an exhaust system according to the disclosure,

[0030] FIG. 2 shows the exhaust system according to the disclosure in a view from above,

[0031] FIG. 3 shows a perspective view of the exhaust system from FIG. 2, wherein a sound line and a sound coupling-in line are represented transparent,

[0032] FIG. 4 shows the exhaust system from FIG. 2 in a view from above, wherein the sound line and the sound coupling-in line are omitted,

[0033] FIG. 5 shows a perspective view of the exhaust system from FIG. 2, wherein, as in FIG. 4, the sound line and the sound coupling-in line are omitted,

[0034] FIG. 6 shows a schematic detail view of a radial rib of the exhaust system from FIG. 2,

[0035] FIG. 7 shows a schematic detail view of a radial rib of the exhaust system from FIG. 2 according to an alternative design and

[0036] FIG. 8 shows a schematic detail view of a radial rib of the exhaust system from FIG. 2 according to a further alternative design.

DETAILED DESCRIPTION

[0037] FIG. 1 shows a motor vehicle 10 with an internal combustion engine 12 which is coupled to an exhaust system 14. Thus, the exhaust gas produced by the internal combustion engine 12 is conducted into the surroundings 16 via the exhaust system 14.

[0038] The exhaust system comprises an exhaust-gas line 18 routing the exhaust gas and an active silencing device 20.

[0039] The active silencing device 20 has a sound-generating unit 22 which comprises, for example, a loudspeaker and a sound line 24. A sound coupling-in line 26 is connected to the sound line 24 downstream.

[0040] A center axis of the sound line 24 runs substantially along a radial direction of the sound coupling-in line 26. The center axes of the sound line 24 and the sound coupling-in line 26 are thus substantially perpendicular to each other.

[0041] Furthermore, the sound coupling-in line 26 surrounds the exhaust-gas line 18 substantially concentrically on the outside. The center axes of the sound coupling-in line 26 and the exhaust-gas line 18 are thus substantially coincident.

[0042] The active silencing device 20, more precisely the sound-generating unit 22, is acoustically coupled to an exhaust gas flow present inside the exhaust-gas line 18. Here, sound generated by the sound-generating unit 22 is conducted into the sound coupling-in line 26 via the sound line 24 and thus passes into an annular space which is formed by the sound coupling-in line 26 and the exhaust-gas line 18.

[0043] The portion of the exhaust-gas line 18 running inside this annular space can be subdivided into an axial portion facing the sound line 24 and an axial portion, connected downstream thereto, facing away from the sound line 24.

[0044] In the embodiment represented, the axial portion facing the sound line 24 and the axial portion facing away from the sound line 24 are directly adjacent to each other.

[0045] Here, a first perforation 38 is provided in the axial portion facing away from the sound line 24. The axial portion facing the sound line 24 is designed perforation-free in a portion, as will be explained later.

[0046] The first perforation 38 runs around the whole periphery of the axial portion facing away from the sound line 24.

[0047] Here, the openings of the first perforation 38 have a substantially round cross section. Within the axial portion facing the sound line 24, the exhaust-gas line 18 furthermore comprises a peripheral portion 28a facing the sound line 24 and a peripheral portion 28b facing away from the sound line 24. In the embodiment example represented, the two peripheral portions 28a, 28b are complementary to each other to form the whole periphery of the exhaust-gas line 18.

[0048] A second perforation 30 is provided in the peripheral portion 28b facing away from the sound line 24. The peripheral portion 28a facing the sound line 24 is designed perforation-free.

[0049] The sound generated by the sound-generating unit 22 which has already reached the abovementioned annular space, can thus interact with the exhaust gas flow present inside the exhaust-gas line 18 via the first perforation 38 and/or the second perforation 30.

[0050] Here, the openings comprised by the second perforation 30 each have a substantially rectangular cross section, wherein the short sides of the rectangle are each oriented in peripheral direction and the long sides of the rectangle are each oriented in axial direction of the exhaust-gas line 18.

[0051] Furthermore, the exhaust-gas line 18 has an axial bend 32 in an area upstream of the sound coupling-in line 26 which is designed as a 90 bend in the embodiment example represented.

[0052] The second perforation 30 and the axial bend 32 are arranged relative to each other such that the second perforation 30 is positioned downstream of a convex area of the axial bend 32.

[0053] Moreover, the exhaust system 14 represented comprises a radial rib 34 in each of the border areas between the peripheral portion 28b facing away from the sound line 24 and the peripheral portion 28a facing the sound line 24.

[0054] These can be designed in different ways.

[0055] In the variant according to FIG. 6, the radial rib 34 is attached to an inner surface of the sound coupling-in line 26 and extends in the direction of the exhaust-gas line 18. Here, a radial distance 36 can be provided between the end of the radial rib 34 lying inside and the exhaust-gas line 18. Equally, the radial rib 34 can touch the exhaust-gas line 18 or be connected thereto.

[0056] Alternatively, according to FIG. 7, the radial rib 34 can be attached to the exhaust-gas line 18 and extend in the direction of the sound coupling-in line 26. A radial distance 36 can again be provided which results between the outer end of the radial rib 34 and the sound coupling-in line 26. It is equally conceivable that the radial rib 34 touches the sound coupling-in line 26 with its outer end or is connected to same.

[0057] Instead of a single radial rib 34 in each border area between the peripheral portion 28a facing the sound line 24 and the peripheral portion 28b facing away from the sound line 24, a radial rib pair can also be provided which comprises radial ribs 34a, 34b. In this connection, the radial rib 34a is attached to the sound coupling-in line 26 and extends in the direction of the exhaust-gas line 18. In contrast, the radial rib 34b is attached to the exhaust-gas line 18 and extends in the direction of the sound coupling-in line 26.

[0058] In peripheral direction, the radial ribs 34a, 34b are only slightly spaced apart from each other or touch each other.

[0059] In radial direction, the radial rib 34a radiating from the sound coupling-in line 26 has a radial distance 36a from the exhaust-gas line 18 at its inner end. The radial rib 34b radiating from the exhaust-gas line 18 leaves a radial distance 36b free between its outer end and the sound coupling-in line 26.

[0060] In all variants, the radial ribs 34, 34a, 34b are shorter in an axial direction of the exhaust-gas line 18 and of the sound coupling-in line 26 arranged concentric thereto than the sound coupling-in line 26. Thus, there is an axial portion of the sound coupling-in line 26 in which there can be flow around the radial ribs 34, 34a, 34b in peripheral direction of the exhaust-gas line 18. To be more precise, the radial ribs 34, 34a, 34b extend merely in the area of the second perforation 30.

[0061] The mode of operation of the exhaust system 14 is as follows.

[0062] The sound generated by the sound-generating unit 22 flows via the sound line 24 into the sound coupling-in line 26. There, it enters into the inside of the exhaust-gas line 18 via the openings of the first perforation 38. Furthermore, after the sound has flowed around the radial ribs 34, 34a, 34b in the area of the first perforation 38, it also passes into the inside of the exhaust-gas line 18 via the openings of the second perforation 30. In this way, a sound carried by the exhaust gas flow inside the exhaust-gas line 18 is actively muffled.

[0063] However, hot exhaust gas can also flow via the openings of the first perforation 38 and the second perforation 30 from the inside of the exhaust-gas line 18 into the annular space formed by the exhaust-gas line 18 and the sound coupling-in line 26. The active silencing device 20 and in particular the sound-generating unit 22 are to be protected against these hot exhaust gases.

[0064] Exhaust gas exiting via the openings of the second perforation 30 must first flow around the radial ribs 34, 34a, 34b on its path in the direction of the sound-generating unit 22. Here, the radial ribs 34, 34a, 34b represent a flow obstacle on the one hand and cool the exhaust gas on the other.

[0065] In addition, because of the flow ratios inside the exhaust-gas line 18, a large part of the exhaust gas which has exited via the openings of the second perforation 30 is conducted back inside the exhaust-gas line 18 via the openings of the first perforation 38. This is due to the fact that inside the exhaust-gas line 18 a higher pressure prevails in the area of the second perforation 30 than in the area of the first perforation 38. In the annular space, the pressure ratios are reversed, with the result that a higher static pressure prevails in the area of the first perforation 38. This also serves to protect the sound-generating unit 22 against high temperatures.

[0066] A direct flow of hot exhaust gas into the sound-generating unit 22 is also prevented in that the peripheral portion 28a facing the sound line 24 is designed perforation-free.

[0067] 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.