Exhaust-gas system

Abstract

An exhaust-gas system for a vehicle having an internal combustion engine includes a Helmholtz resonator and two exhaust-gas lines extending toward the resonator. The resonator has two neck openings to a resonator volume. Each neck opening is coupled to one of the exhaust-gas lines, and the resonator is tuned to damp a dominant engine order.

Claims

1. An exhaust-gas system for a vehicle having an internal combustion engine, comprising: a Helmholtz resonator within a resonator housing defining a resonator volume, the resonator being tuned for damping a dominant engine order; and two exhaust-gas lines extending laterally past the resonator housing, wherein the resonator housing has two neck openings to the resonator volume, each neck opening being coupled to a respective one of the two exhaust-gas lines such that exhaust does not flow through the resonator volume.

2. The exhaust-gas system as claimed in claim 1, wherein the resonator housing is configured separately from other component housings of the exhaust-gas system, and the housing is arranged spaced apart from a rear region of the vehicle.

3. The exhaust-gas system as claimed in claim 1, further comprising: a flap in each case arranged in a region between the exhaust-gas line and the resonator volume, which flap is configured for the at least partial opening and/or closing of the neck opening in each case.

4. The exhaust-gas system as claimed in claim 3, wherein each exhaust-gas line in a through-flow direction of the exhaust-gas lines downstream of the resonator has at least two exhaust-gas outlet openings, and at least one exhaust-gas outlet opening in each case is provided with an exhaust-gas flap, by which the exhaust-gas outlet opening is reversibly closable.

5. The exhaust-gas system as claimed in claim 4, wherein a common cross section of the exhaust-gas outlet openings for each exhaust-gas line is of a same size as the cross section of the exhaust-gas line.

6. The exhaust-gas system as claimed in claim 3, further comprising: an actuator for joint actuation of the flap arranged between the resonator volume and the respective exhaust-gas line.

7. The exhaust-gas system as claimed in claim 4, further comprising: an actuator for joint actuation of the exhaust-gas flap arranged in a respective outlet opening.

8. The exhaust-gas system as claimed in claim 1, further comprising: a sound-damping device provided in a through-flow direction of the exhaust-gas lines downstream of the resonator.

9. The exhaust-gas system as claimed in claim 1, wherein the resonator volume is divided by a partition wall into at least two partial volumes.

10. The exhaust-gas system as claimed in claim 9, wherein the partition wall has an aperture connecting the partial volumes.

11. The exhaust-gas system as claimed in claim 1, wherein the resonator has a housing body made of a plastics material.

12. The exhaust-gas system as claimed in claim 1, further comprising: a further neck opening extending, in each case, from a respective exhaust-gas line to the resonator volume, wherein at least one of the neck openings for each exhaust-gas line is provided with a flap for the at least partial opening and/or closing of the neck opening in each case.

13. A method of operating an exhaust-gas system for a vehicle having an internal combustion engine, wherein the exhaust-gas system comprises: a Helmholtz resonator within a resonator housing defining a resonator volume, the resonator being tuned for damping a dominant engine order; and two exhaust-gas lines that extend laterally past the resonator housing, wherein the resonator housing has two neck openings into the resonator volume, each neck opening being coupled to a respective one of the two exhaust-gas lines such that exhaust does not flow through the resonator volume, wherein the method comprises the acts of: providing the exhaust-gas system with an exhaust-gas flap in an exhaust-gas outlet opening; and closing the exhaust-gas flap when the vehicle is coasting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic representation of an embodiment of an exhaust-gas system with two exhaust-gas lines and four exhaust-gas outlet openings and a Helmholtz resonator.

(2) FIG. 2 shows a representation similar to that according to FIG. 1 with an additional rear muffler for each exhaust-gas line of the exhaust-gas system.

(3) FIG. 3 shows a representation similar to that in FIG. 1 with a switchable exhaust-gas flap in an exhaust-gas outlet opening for each exhaust-gas line.

(4) FIG. 4 shows a representation similar to that according to FIG. 3 with an additional rear muffler for each exhaust-gas line of the exhaust-gas system.

(5) FIG. 5 shows a representation similar to that according to FIG. 1 with a resonator flap for each neck opening.

(6) FIG. 6 shows a representation similar to that according to FIG. 5 with an additional rear muffler for each exhaust-gas line of the exhaust-gas system.

(7) FIG. 7 shows a representation similar to that according to FIG. 6 with an additional exhaust gas flap in an exhaust-gas outlet opening for each exhaust-gas line of the exhaust-gas system.

(8) FIG. 8 shows a representation similar to that according to FIG. 7 with an additional rear muffler for each exhaust-gas line of the exhaust-gas system.

(9) FIG. 9 shows a representation of an arrangement similar to that according to FIG. 8 with a further neck opening in the direction of the resonator capacity starting from the exhaust-gas line, in addition to the neck opening for each exhaust-gas line that can be switched using a resonator flap.

(10) FIG. 10 shows a representation of an arrangement similar to that according to FIG. 6 which differs in that only one exhaust-gas outlet opening is provided for each exhaust gas line side.

(11) FIG. 11 shows a representation of an arrangement similar to that according to FIG. 9, but without an exhaust-gas flap in the region of the exhaust-gas outlet opening.

(12) FIG. 12 shows a representation of an arrangement similar to that according to FIG. 5, in turn with only one exhaust-gas outlet opening for each exhaust-gas line side.

DETAILED DESCRIPTION OF THE DRAWINGS

(13) FIG. 1 in the drawing shows a schematic representation of an embodiment of a two-stage exhaust-gas system 1 with a Helmholtz resonator 2.

(14) The two-stage exhaust-gas system 1 has two exhaust-gas lines 3 with a resonator housing 4 arranged in the region between the two exhaust-gas lines 3. The two exhaust-gas lines 3 start from an internal combustion engine (not depicted in greater detail) of a vehicle (likewise not represented in greater detail). The resonator housing creates a resonator volume 5 of the Helmholtz resonator 2.

(15) The resonator housing 4 has two branch lines 6 extending in the direction of the exhaust-gas lines 3, said branch lines forming neck openings 7 of the Helmholtz resonator 2.

(16) The resonator housing 4 does not have exhaust gas flowing through it, which means that during operation of the exhaust-gas system 1 it is not exposed to hot exhaust gas with a heat flow passing through the resonator 2 and can therefore be made of a plastics material.

(17) The Helmholtz resonator 2 is tuned via an arrangement of the resonator volume adapted to the respective internal combustion engine, the length of the resonator neck, in other words the length of the branch line 6, and the diameter of the resonator neck. This tuning means that the resonator 2 is designed for the frequency which has the highest sound-pressure level in quantitative terms of an opening level measured during a test run or a licensing run of the vehicle, for example.

(18) This may, for example, involve a test run being carried out using a vehicle without a Helmholtz resonator and the opening level measured in a test section being tested for the frequency which generates the highest sound-pressure level during the test run. A corresponding tuning of the Helmholtz resonator to this frequency means that this frequency can then be correspondingly reduced during a test run with the Helmholtz resonator, without sound-damping devices which work according to the reflection, absorption or resonance method being necessary.

(19) In the case of the embodiment shown in FIG. 1, the exhaust-gas system 1 has two exhaust-gas outlet openings 8 for each exhaust-gas line 3 or exhaust-gas line side, wherein the exhaust-gas system 1 according to the invention is not limited to this number of exhaust-gas outlet openings, but may also have only one exhaust-gas outlet opening 8 for each exhaust-gas line 3, as is the case, for example, with the embodiments of the exhaust gas line according to FIG. 10 through FIG. 12.

(20) FIG. 2 shows a modified embodiment of the exhaust-gas system 1 with a rear muffler 9 for each exhaust-gas line side. With the rear muffler 9, the acoustic pattern that can be acoustically perceived by the vehicle user can be influenced, for example in the direction of a sporting acoustic pattern or one enriched with low frequencies.

(21) FIG. 3 shows an embodiment of an exhaust-gas system 1, in which two exhaust-gas outlet openings 8 are each provided with a reversibly closable exhaust-gas flap 10. The exhaust-gas flap 10 may be actuated via a device (not shown in greater detail) for the opening and closing of the exhaust-gas outlet opening 8. The device may, for example, be implemented by the engine control system of the internal combustion engine, which delivers a control signal for closing the exhaust-gas flap 10 to an actuating device of the exhaust-gas flap 10 if the vehicle, and therefore the internal combustion engine, starts coasting. The exhaust-gas flap 10, which is then closed, prevents the emission of frequencies that can be perceived as droning.

(22) FIG. 4 shows a further modified embodiment of the exhaust-gas system 1 with two exhaust-gas flaps 10, one of which is provided on an exhaust-gas outlet opening 8, and a rear muffler 9 provided for each exhaust-gas line side. The acoustic pattern of the internal combustion engine can be influenced by the rear muffler 9, as has already been mentioned above.

(23) FIG. 5 shows an embodiment of the exhaust-gas line 1 with two exhaust-gas lines 3 and a Helmholtz resonator 2 inserted between the exhaust-gas lines 3, as has already been explained with reference to FIG. 1 in the drawing.

(24) Unlike in the embodiment according to FIG. 1, the Helmholtz resonator 2 according to FIG. 5 can be switched, so with regard to its damping function into a damping and non-damping state. To this end, the neck openings 7 can be varied using a flap or resonator flap 11 arranged in the region of a neck opening 7 in each case, in such a manner that the neck openings 7 can be blocked or in other words closed or opened.

(25) In the case of neck openings 7 blocked by activating the resonator flaps 11, the damping action of the resonator 2 is eliminated and, in the case of neck openings 7 which are made open or passable by actuating the resonator flaps 11, the resonator 2 performs the damping function described above.

(26) In all embodiments of the exhaust-gas system 1 with resonator flaps 11, it is also provided according to the present invention that the resonator flaps 11 can not only be opened or closed digitally, so to speak, but can also adopt angled positions between the opening state and the closing state, as a result of which the degree of damping of the resonator 2 can be variably set. By changing the degree of opening of the resonator flaps 11, the resonance frequency of the damping does not change, but only the degree of damping corresponding to the opening angle of the resonator flaps 11 that has been set.

(27) FIG. 6 shows an embodiment of an exhaust-gas system 1 with controllable or variable resonator flaps 11, as have just been described, and a rear muffler 9 for each exhaust gas line side, with which the acoustic pattern of the exhaust-gas system can be configured.

(28) FIG. 7 shows an embodiment of an exhaust-gas system 1 with controllable or variable resonator flaps 11 and additional exhaust-gas flaps 10 in the region of two exhaust-gas outlet openings 8. As has already been explained above, apart from influencing the acoustic pattern of the internal combustion engine by switching the resonator 2 on or off, the damping can also be changed while the vehicle is coasting, in that the exhaust gas flaps 10 are actuated by the engine control system, for example, in order to close the corresponding exhaust-gas outlet opening 8.

(29) A further reduction in the noise level emitted by the exhaust-gas system 1 can be achieved in that the exhaust-gas transmission diameter of the exhaust-gas outlet opening 8 without the exhaust-gas flap 10 is substantially reduced compared with the diameter of the exhaust-gas line 3, so that through this configuration the acoustic pattern of the internal combustion engine can be changed in a broad setting range.

(30) FIG. 8 shows an embodiment of an exhaust-gas system 1 similar to that according to FIG. 7 with a rear muffler 9 provided in addition for each exhaust-gas line side, arranged downstream of the resonator 2, for influencing the acoustic pattern of the engine.

(31) FIG. 9 shows a further modified embodiment of an exhaust-gas system 1 in which, apart from two first neck openings 7 controllable or variable by means of two resonator flaps 11, two further neck openings 12 are provided, namely a neck opening 12 for each exhaust-gas line 3, which neck opening is formed by a branch line 13 arranged between the respective exhaust-gas line 3 and the resonator housing 4.

(32) This embodiment creates a switchable or variable resonator 2 which also performs the function of a basic resonator. The term basic resonator in this case should be understood to mean a resonator tuned to a first frequency, the basic frequency, the resonator being configured for the damping thereof. The basic frequency in this case is determined by, among other things, the opening diameter of the neck opening 12, so that the resonator depicted in FIG. 9 of the drawing always dampens the basic frequency, as the branch lines 13 are constantly open.

(33) The basic frequency may, for example, be a frequency which determines in a dominant manner a sound level to be observed during a test run or licensing run and which is therefore permanently damped. If the exhaust-gas flaps 11 are open, the resonator can also still dampen a second disruptive frequency. The branch lines 13 and the resonator flaps 11 can be tuned in relation to their length and the common cross section to a required damping frequency, which may also be, for example, the damping frequency required for the licensing run or a second frequency found to be disruptive in a given driving mode.

(34) FIG. 10 to FIG. 12 show embodiments of exhaust-gas systems with two exhaust-gas lines 3 and a resonator 2 in each case, each having only one outlet pipe or an exhaust gas outlet opening 8.

(35) The resonator 2 depicted in FIG. 10 has two controllable or variable resonator flaps 11, the function of which corresponds to the resonator flaps 11 explained in connection with FIG. 5 in the drawing.

(36) FIG. 11 shows an embodiment of an exhaust-gas system 1 similar to that according to FIG. 9 with additional neck openings 12, which are always open, and resonator flaps 11. While the exhaust-gas system depicted in FIG. 9 also still has two exhaust-gas flaps 10 on two exhaust-gas outlet openings 8 which are provided to dampen droning frequencies when the vehicle is coasting, for example, the exhaust-gas system shown in FIG. 11, as well as the exhaust-gas system according to FIG. 9, has two rear mufflers 9, but not the exhaust-gas flaps 10.

(37) The exhaust-gas system depicted in FIG. 11 is provided for arrangement on an internal combustion engine, for example, which does not generate any disruptive droning frequencies while coasting, so that the exhaust-gas flaps 11 can be omitted to make cost reductions.

(38) Finally, FIG. 12 shows an exhaust gas system with two exhaust-gas lines 3 and a resonator 2 that can be controlled and varied via the resonator flaps 11, so that in this embodiment too the damping degree of the resonator 2 can be varied in accordance with the opening angle of the resonator flaps 11. In order to reduce costs compared with the exhaust-gas system depicted in FIG. 10, the exhaust-gas system depicted in FIG. 12 does not have a rear muffler 9 for each exhaust-gas line side, however, as is depicted in the embodiment according to FIG. 10.

(39) Although in the embodiments of the exhaust-gas system shown in the figures, apart from the Helmholtz resonator in each case, no further sound-damping housings are depicted. However, in the exhaust-gas system in each case a further sound-damping device in the form of a mid-muffler can be arranged in the region upstream of the Helmholtz resonator.

(40) In the respective embodiment with exhaust-gas flaps in the exhaust-gas outlet opening, the exhaust-gas flap takes over the damping of disruptive frequencies, particularly when the engine is coasting. In an embodiment with additional resonator flaps the noise level at the exhaust-gas outlet openings can be changed over wide ranges and the acoustics of the exhaust-gas system can thereby be particularly influenced, as a resonator which is at least partially open due to the opening of the resonator flaps takes over the function of a cross-talk point, so that particularly with an internal combustion engine in V-configuration, a clearly different acoustic pattern results than with an exhaust-gas system without a cross-talk point.

(41) A resonator provided with additional, always open neck openings can also be used for damping a disruptive frequency occurring when the resonator flaps are closed.

(42) Since the resonator does not have hot exhaust gas flowing through it, it can be produced from a plastics material, for example, as a result of which a substantial reduction in the dead weight of the resonator results. Through the use of plastic or also of a carbon-fiber-reinforced plastic, for example, the resonator housing can be adapted to the geometry of the underside of the vehicle and therefore also be moved from the rear region of the vehicle toward the center of the vehicle, as a result of which the crash behavior of the vehicle is improved.

LIST OF REFERENCE NUMBERS

(43) 1. Exhaust-gas system 2. Helmholtz resonator 3. Exhaust-gas lines 4. Resonator housing 5. Resonator volume 6. Branch lines 7. Neck opening 8. Exhaust-gas outlet opening 9. Rear muffler 10. Exhaust-gas flap 11. Flap, resonator flap 12. Neck opening 13. Branch line

(44) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.