EXHAUST GAS SYSTEM FOR AN INTERNAL COMBUSTION ENGINE OF A MOTOR VEHICLE

Abstract

An exhaust gas system for an internal combustion engine of a motor vehicle includes at least one exhaust gas line and an active sound-generation device, which comprises a sound line with a mouth that opens into the exhaust gas line and is connected to an electrical sound source. A housing surrounds at least one portion of the exhaust gas line arranged downstream of the mouth of the sound line into the exhaust gas line when viewed in a flow direction of the exhaust gas. The said housing is connected to an error sensor and a cavity is formed between an outer side of the exhaust gas line and an inner side of the housing. The at least one portion of the exhaust gas line extending in the housing has at least one opening that opens into the cavity.

Claims

1. An exhaust gas system for an internal combustion engine of a motor vehicle comprising: at least one exhaust gas line; an active sound-generation device comprising a sound line having a mouth which opens into the exhaust gas line and is connected to an electrical sound source; and a housing that surrounds at least one portion of the exhaust gas line arranged downstream of the mouth of the sound line when viewed in a flow direction of exhaust gas, said housing being connected to an error sensor, wherein a cavity is formed between an outer side of the exhaust gas line and an inner side of the housing, and wherein the at least one portion of the exhaust gas line extending in the housing has at least one opening that opens into the cavity.

2. The exhaust gas system according to claim 1, wherein the at least one opening forms a perforated region.

3. The exhaust gas system according to claim 2, wherein the perforated region comprises slots, holes, and/or microperforations.

4. The exhaust gas system according claim 1, wherein the at least one opening runs in a circumferentially closed manner to form two spaced-apart line portions.

5. The exhaust gas system according to claim 1, wherein the at least one opening forms a space between an end of the exhaust gas line and a downstream end of the housing.

6. The exhaust gas system according to claim 1, wherein the exhaust gas line and the sound line together form a double-D pipe in one portion.

7. The exhaust gas system according to claim 6, wherein the housing coaxially surrounds the exhaust gas line.

8. The exhaust gas system according to claim 1, wherein an absorption material is arranged in the cavity.

9. The exhaust gas system according to claim 1, wherein the error sensor is in flow communication with the cavity via a line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a schematic diagram of an exhaust gas system according to the invention for an internal combustion engine of a motor vehicle,

[0023] FIG. 2 is a cross section through an exhaust gas line and a sound line of the exhaust gas system in a region upstream of a mouth of the sound line into the exhaust gas line,

[0024] FIG. 3 is a schematic sectional view of a portion from one example embodiment of the exhaust gas system according to the invention,

[0025] FIG. 4 is a schematic sectional view of a portion from another example embodiment of the exhaust gas system according to the invention,

[0026] FIG. 5 is a schematic sectional view of a portion from another example embodiment of the exhaust gas system according to the invention,

[0027] FIG. 6 is a schematic sectional view of a portion from another example embodiment of the exhaust gas system according to the invention,

[0028] FIG. 7 is a schematic sectional view of a portion from another example embodiment of the exhaust gas system according to the invention, and

[0029] FIG. 8 is a schematic sectional view of a portion from another example embodiment of the exhaust gas system according to the invention.

DETAILED DESCRIPTION

[0030] FIG. 1 schematically shows an exhaust gas system 10 according to the invention for an internal combustion engine of a motor vehicle.

[0031] The exhaust gas system 10 comprises an exhaust gas line 12 and an active sound-generation device 14 which comprises a sound line 16 which opens into the exhaust gas line 12 and is connected to an electrical sound source 18. The sound source 18 is a loudspeaker, for example. Via the sound-generation device 14, an undesirable engine noise can be muffled and/or a desired engine noise can be constructed. For example, customers associate certain noises with high engine performance or a high-quality engine. In a portion arranged downstream of a mouth 19 of the sound line 16 into the exhaust gas line 12 when viewed in a flow direction of the exhaust gas, the exhaust gas line 12 is surrounded by a housing 20, wherein a cavity 22 is formed between an outer side of the exhaust gas line 12 and an inner side of the housing 20. By way of example, the housing 20 is an elongate sleeve which surrounds, in particular coaxially encloses, the exhaust gas line 12.

[0032] The portion of the exhaust gas line 12 extending in the housing 20 has at least one opening 30 which opens into the cavity 22. FIGS. 3 to 8 schematically show various possible forms of the opening 30. The openings 30 are acoustically transparent and allow sound waves to propagate out of the exhaust gas line 12 into the cavity 22, where they undergo superposition.

[0033] The housing 20 is in flow communication with an error sensor 24, for example via a flexible hollow line 32. The error sensor 24 is a microphone, for example.

[0034] The mode of operation of the exhaust gas system 10 and the sound-generation device 14 will be explained below:

[0035] During engine operation, exhaust gas flows in the exhaust gas line 12 towards an outlet end 26 of the exhaust gas system 10. In the process, at least some of the noise generated by the engine itself propagates in the exhaust gas line 12 in the form of sound waves. At the same time, the sound waves of the noises generated by the sound source 18 propagate in the sound line 16 and, downstream of the mouth 19, also in the exhaust gas line 12. In the region in which the exhaust gas line 12 and the sound line 16 run in parallel, the sound waves emanating from the engine and the sound source 18 are superposed. This actively influences the engine noise.

[0036] In the embodiment shown, the exhaust gas line 12 and the sound line 16 are merged in a Y-shaped portion and, in a region downstream of the Y-junction, extend in one portion in parallel with and separately from one another in a double-D pipe 28. This portion terminates upstream of the housing 20. FIG. 2 shows a cross section through the double-D pipe 28.

[0037] To obtain an optimum engine noise, feedback is provided. For this purpose, the error sensor 24 measures the pressure conditions in the cavity 22, in particular pressure fluctuations and the static pressure, upon which the sound waves generated by the sound source 18 are adapted as required.

[0038] Since the error sensor 24 is in flow communication with the housing 20, the error sensor 24 can identify an error signal to a particularly high degree of accuracy.

[0039] FIGS. 3 to 8 illustrate various embodiments of the invention which differ in particular on account of the shape of the opening 30. In each case a part of the exhaust gas system 10 that comprises the housing 20 is shown schematically.

[0040] FIG. 3 shows an embodiment according to the invention of the exhaust gas system 10 in which the opening 30 forms a perforated region 34 in the exhaust gas line 12. Here, the perforated region 34 comprises holes 36. Alternatively or additionally, however, the perforated region 34 can be formed by slots or microperforations. Sound waves can propagate along the perforated region 34 out of the exhaust gas line 12 into the cavity 22 of the housing 20.

[0041] FIG. 4 shows a further embodiment of the exhaust gas system 10 which differs from the embodiment shown in FIG. 3 in that an absorption material 38 is additionally provided in the cavity 22. This serves as a physical filter, in particular as a high-frequency filter, in order to shield the error sensor 24 against high-frequency sound waves. In addition, the absorption material 38 muffles high-frequency external noises at the outlet end 26 of the exhaust gas line 12.

[0042] FIG. 5 shows a further embodiment of the exhaust gas system 10 which differs from the embodiment shown in FIG. 3 in that, at its outlet end 26, the exhaust gas line 12 terminates flush with a downstream end of the housing 20. This achieves a compact design of the exhaust gas system 10. At the same time, the housing 20 forms a pipe end cover for the exhaust gas line 12. This is advantageous in that the number of required components is reduced, whereby the exhaust gas system 10 is cost-effective to produce.

[0043] In the embodiment of the exhaust gas system 10 shown in FIG. 6, the exhaust gas line 12 terminates in the housing 20. As a result, there is formed in addition to the perforated region 34 an additional opening 30 which forms a space between an end 26 of the exhaust gas line 12 and a downstream end of the housing 20, in which an outlet opening of the housing 20 is provided.

[0044] Therefore, the sound waves can propagate not only through the perforated region 34 into the cavity 22 of the housing 20, but also through a gap formed between the housing and the exhaust gas line 12. As a result, the sound waves can undergo even more effective superposition in the housing 20.

[0045] FIG. 7 shows a further embodiment of the exhaust gas system 10, which differs from the embodiment shown in FIG. 6 in that there is no perforated region 34; instead, the opening 30 is formed solely by a space between an end 26 of the exhaust gas line 12 and a downstream end of the housing 20. Here also, the right-hand wall of the housing 20 has an outflow opening. This embodiment is particularly cost-effective to produce.

[0046] FIG. 8 shows a further embodiment of the exhaust gas system 10, in which the opening 30 runs in a circumferentially closed manner so as to form two spaced-apart line portions. This opening 30 has a maximum possible acoustic transparency, with the result that sound waves can propagate into the cavity 22 unhindered.

[0047] Although an embodiment of this invention has 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.