Exhaust system for an internal combustion engine

Abstract

An exhaust system for an internal combustion engine includes a muffler, a first exhaust pipe which is connected to the muffler for sound damping, and a second exhaust pipe which extends in terms of flow in parallel relation to the first exhaust pipe and extends through first muffler in the absence of a flow communication with the first muffler. The first and second exhaust pipes originate from a common exhaust pipe. A switching valve adjusts hereby a throughflow cross section of the second exhaust pipe.

Claims

1. An exhaust system for an internal combustion engine, comprising: a first muffler; a first exhaust pipe connected to the first muffler for sound damping; a second exhaust pipe extending in terms of flow in parallel relation to the first exhaust pipe and configured to extend through the first muffler in the absence of a flow communication with the first muffler, said first and second exhaust pipes originating from a common exhaust pipe; a switching valve configured to adjust a throughflow cross section of the second exhaust pipe; and at least one second muffler disposed upstream of the first muffler, said first exhaust pipe connected to the second muffler for sound damping, said second exhaust pipe extending through the second muffler in the absence of a flow communication with the second muffler.

2. The exhaust system of claim 1, wherein the switching valve is configured as an exhaust gas recirculation valve, further comprising an exhaust gas recirculation pipe disposed upstream of the switching valve branching off the second exhaust pipe or the common exhaust pipe.

3. The exhaust system of claim 1, wherein the switching valve is disposed downstream of the muffler.

4. The exhaust system of claim 1, wherein the first muffler is constructed as rear muffler.

5. The exhaust system of claim 1, wherein the first exhaust pipe causes a pressure loss which is greater than a pressure loss caused by the second exhaust pipe, when the switching valve is open.

6. The exhaust system of claim 1, wherein the switching valve is constructed as discretely switching valve or as proportional valve.

7. The exhaust system of claim 1, further comprising an exhaust gas aftertreatment device disposed in at least one of the first and second exhaust pipes.

8. The exhaust system of claim 1, further comprising a sound tube disposed downstream of the switching valve and feeding into the second exhaust pipe.

9. The exhaust system of claim 1, wherein the first and second exhaust pipes feed into separate end pipes downstream of the first muffler.

10. The exhaust system of claim 1, wherein the first exhaust pipe is of discontinuous configuration inside the first muffler to define a first sub-section and a second sub-section to enable exhaust to enter an inner volume of the first muffler from the first sub-section and to enable exhaust to enter the second sub-section from the inner volume of the first muffler.

11. The exhaust system of claim 1, wherein the first and second sub-sections of the first exhaust pipe overlap one another so as to extend side-by-side.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

(2) FIG. 1 is a schematic illustration of a portion of an exhaust system for an internal combustion engine in accordance with the present invention; and

(3) FIG. 2 is a detailed view, on an enlarged scale, of a muffler of the exhaust system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(4) Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments may be illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

(5) Turning now to the drawing, and in particular to FIG. 1, there is shown a schematic illustration of a portion of an exhaust system for an internal combustion engine in accordance with the present invention, generally designated by reference numeral 1. The exhaust system 1 includes a first exhaust pipe 2 and a second exhaust pipe 3. Both exhaust pipes 2, 3 originate from a common exhaust pipe 4 via which the exhaust pipes 2, 3 are in flow communication with the internal combustion engine. In the non-limiting example of FIG. 1, the exhaust system 1 further includes a muffler 5 and a muffler 6, with the muffler 6 representing a rear muffler. The exhaust pipes 2, 3 feed downstream of the muffler 6 into end pipes 7, 8, respectively, via which exhaust, flowing in the exhaust pipes 2, 3, is released into the outside environment. Provision may be made for optional aftertreatment devices 10, 11 in the exhaust pipes 2, 3, respectively. The aftertreatment devices 10, 11 may, for example, each be configured as catalytic converter or particular filter.

(6) As is readily apparent, the exhaust pipes 2, 3 extend each through both mufflers 5, 6. However, only the first exhaust pipe 2 is connected to the mufflers 5, 6 for sound damping. The second exhaust pipe 3, while extending through the mufflers 5, 6, is decoupled therefrom, i.e. there is no flow communication. Thus, vibrations in the exhaust flowing in the first exhaust pipe 2 are damped by the mufflers 5, 6 to a greater degree that vibrations in the exhaust flowing in the second exhaust pipe 3. Moreover, the mufflers 5, 6 cause a pressure loss in the first exhaust pipe 2, so that the first exhaust pipe 2 overall has a greater pressure loss than the second exhaust pipe 3.

(7) A throughflow cross section of the second exhaust pipe 3 is advantageously adjustable via a switching valve 12. Using the switching valve 12, the pressure loss of the second exhaust pipe 3 and thus the exhaust gas back pressure in the second exhaust pipe 3 can be adjusted. The switching valve 12 can be constructed as discretely switching valve or as proportional valve. A sound tube 13 may, optionally, also be provided downstream of the muffler 6 or downstream of both mufflers 5, 6, but upstream of the end pipe 8, for feeding into the second exhaust pipe 3. For example, a sound chamber 14 is in flow communication with the second exhaust pipe 3 via the sound tube 13. A loudspeaker or the like may be arranged in the sound chamber 14. Vibrations may be applied upon exhaust, flowing through the second exhaust pipe 3, via the sound tube 13, so that the noise level of the internal combustion engine can be influenced.

(8) An exhaust gas recirculation pipe 15 may branch off the second exhaust pipe 3 or the common exhaust pipe 4 upstream of the switching valve 12. This is shown in FIG. 1 purely by way of example. The exhaust gas recirculation pipe 15 is shown here to branch off the second exhaust pipe 5 upstream of the mufflers 5, 6.

(9) FIG. 2 shows a detailed view, on an enlarged scale, of the muffler 5 of the exhaust system 1. It is to be understood that the principles described in the following description with respect to the muffler 5 are generally applicable to the muffler 6 as well. The muffler 5 has an inner volume 16 which is formed by a housing shell 17, advantageously two housing shells 17 that are fastened to one another, so as to be enclosed in a fluidtight manner against the outside environment. It is readily apparent that the first exhaust pipe 2 is connected in a sound damping manner to the muffler 5. The first exhaust pipe 2 has hereby, for example, a first sub-section 18 and a second sub-section 19. The sub-sections 18, 19 are accommodated in their entirety within the inner volume 16 but not connected in direct fluid communication with one another. Rather, the sub-sections 18, 19 are fluidly connected to one another indirectly via the inner volume 16.

(10) Thus, exhaust conducted via the first exhaust pipe 2 exits inside the muffler 5 from the first sub-section 18 into the inner volume 16, then enters the second sub-section 19, and leaves the muffler 5 via the second sub-section 19 and the first exhaust pipe 2 for subsequent conduction in the direction of the outside environment. The second exhaust pipe 3 is also arranged in the muffler 5 and its inner volume 16. In contrast to the first exhaust pipe 2, the second exhaust pipe 3 extends continuously through the muffler 5 in the absence of any flow communication with the inner volume 16 of the muffler 5. In other words, the second exhaust pipe 3 is decoupled from the muffler 5 and separated from the inner volume 16 so that exhaust flowing through the second exhaust pipe 3 cannot escape into the inner volume 16 or exhaust is unable to enter the second exhaust pipe 3 from the inner volume 16.

(11) As a result of such a configuration of an exhaust system 1 according to the present invention, different exhaust gas back pressures are established in the first and second exhaust pipes 2, 3, when the switching valve 12 fully opens the second exhaust pipe 3. In the presence of a fully open second exhaust pipe 3, exhaust predominantly flows there through. Using the switching valve 12, exhaust flowing via the common exhaust pipe 4 may, however, be split to flow through the first exhaust pipe 2 and the second exhaust pipe 3. Therefore, the noise level of the internal combustion engine can be adjusted and the mass flow rate of exhaust recirculated to the internal combustion engine may be adjusted as well with the assistance of the switching valve 12.

(12) While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.