Muffler for an exhaust system

Abstract

A muffler (1) for an exhaust system of a motor vehicle internal combustion engine has a housing (2), with an exhaust gas inlet (4) and an exhaust gas outlet (5), including a circumferentially extending jacket (16) and end panels (14, 15) each axial ends. A chamber (18) in the housing interior (3), through which exhaust gas flows during operation, is axially limited by intermediate panels (20, 21) at axial ends. The thermal load on the jacket (16) is reduced with an insulating shell (29), arranged in the housing interior, extending in the circumferential direction (17) along the jacket (16). The two intermediate panels (20, 21) are supported on the insulating shell (29), each with an outer panel edge (30, 31). The insulating shell (29) is supported radially on the jacket (16) with a shell edge (33). An insulating gap (35) is formed radially between the jacket and the insulating shell.

Claims

1. A muffler for an exhaust system of an internal combustion engine of a motor vehicle, the muffler comprising: a housing comprising a jacket extending circumferentially in a circumferential direction, a first axial end panel and a second axial end panel; at least one exhaust gas inlet to the housing; at least one exhaust gas outlet to the housing; a first intermediate panel; a second intermediate panel cooperating with the first intermediate panel to form a chamber, in the housing interior, through which exhaust gas flows during the operation of the exhaust system and which is axially limited by the first intermediate panel, at a first axial end, and by the second intermediate panel, at a second axial end; and at least one insulating shell extending in the circumferential direction along the jacket in the housing interior, wherein: the first intermediate panel is supported radially on the insulating shell with a first intermediate panel outer panel edge; the second intermediate panel is supported radially on the insulating shell with a second intermediate panel outer panel edge; the insulating shell is supported radially on the jacket with a shell edge; an insulating gap is formed radially between the jacket and the insulating shell; the insulating shell extends in the circumferential direction over less than 360; the insulating shell has a first shell section; a first panel radial edge of the first intermediate panel is supported at the first shell section; the insulating shell has a second shell section; a second panel radial edge of the second intermediate panel is supported at the second shell section; the jacket has a first jacket section; a first panel radial edge of the first intermediate panel is supported at the first jacket section; the jacket has a second jacket section; and a second panel radial edge of the second intermediate panel is supported at the second jacket section.

2. A muffler in accordance with claim 1, wherein the insulating shell is axially spaced from the first axial end panel and is axially spaced from the second axial end panel.

3. A muffler in accordance with claim 1, wherein the insulating shell extends in the circumferential direction over a maximum of 180.

4. A muffler in accordance with claim 1, wherein the first intermediate panel has a step in which a shell edge passes through the first intermediate panel in an area of at least one transition between the first shell section and the first jacket section.

5. A muffler in accordance with claim 1, wherein the insulating shell has a shell edge with at least one interruption in which the first intermediate panel extends up to the jacket and is supported radially on the jacket in the first jacket section with the panel edge.

6. A muffler in accordance with claim 1, wherein the insulating shell has a shell edge that has two circumferential sections extending in the circumferential direction and two axially extending axial sections, which connect the two circumferential sections to one another.

7. A muffler in accordance with claim 1, wherein the insulating shell has a shell edge that is shaped such that a linear contact is obtained between the shell edge and the jacket.

8. A muffler in accordance with claim 1, wherein: the at least one exhaust gas inlet is connected to a feed line, through which exhaust gas enters the chamber during the operation of the exhaust system; the feed line has an open outlet end; the at least one exhaust gas outlet is connected to a discharge line, through which exhaust gas leaves the chamber during the operation of the exhaust system; the discharge line has an open inlet end; and the chamber comprises at least one of a reflection chamber and an expansion chamber.

9. A muffler in accordance with claim 1, wherein the at least one exhaust gas inlet opens through the jacket into the chamber.

10. A muffler in accordance with claim 8, wherein the at least one exhaust gas inlet opens into the chamber opposite the insulating shell.

11. A muffler in accordance with claim 1, wherein the at least one exhaust gas inlet passes through the jacket in an area of the jacket sections.

12. A muffler in accordance with claim 1, further comprising insulating material arranged in the insulating gap.

13. A muffler in accordance with claim 11, wherein: the insulating shell comprises fixing sections, which mesh with the insulating material without touching the jacket; and the fixing sections are bent out on the insulating shell.

14. A muffler in accordance with claim 1, wherein: the first intermediate panel is welded to the insulating shell; the second intermediate panel is welded to the insulating shell; and the insulating shell is supported loosely on the jacket.

15. A muffler for an exhaust system of an internal combustion engine of a motor vehicle, the muffler comprising: a housing comprising a jacket extending circumferentially in a circumferential direction, a first axial end panel and a second axial end panel; at least one exhaust gas inlet to the housing; at least one exhaust gas outlet to the housing; a first intermediate panel; a second intermediate panel cooperating with the first intermediate panel to form a chamber, in the housing interior, through which exhaust gas flows during the operation of the exhaust system and which is axially limited by the first intermediate panel, at a first axial end, and by the second intermediate panel, at a second axial end; and at least one insulating shell extending in the circumferential direction along the jacket in the housing interior, wherein: the first intermediate panel is supported radially on the insulating shell with a first intermediate panel outer panel edge; the second intermediate panel is supported radially on the insulating shell with a second intermediate panel outer panel edge; the insulating shell is supported radially on the jacket with a shell edge; an insulating gap is formed radially between the jacket and the insulating shell; the first intermediate panel is welded to the insulating shell; the second intermediate panel is welded to the insulating shell; and the insulating shell is supported loosely on the jacket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 shows a highly simplified longitudinal section of a muffler,

(3) FIG. 2 shows a highly simplified cross section of the muffler corresponding to section lines II in FIG. 2,

(4) FIG. 3 shows an enlarged detail III from FIG. 2, and

(5) FIG. 4 shows a radial view of an insulating shell of the muffler.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) Corresponding to FIGS. 1 and 2, a muffler 1 comprises a housing 2, which envelops a housing interior 3 and which has at least one exhaust gas inlet 4 as well as at least one exhaust gas outlet 5. Exhaust gas is fed through the exhaust gas inlet 4 to the housing interior 3 corresponding to an arrow 6 during the operation of an exhaust system, not shown here, in which the muffler 1 is integrated, or during the operation of an internal combustion engine, not shown here, which is equipped with said exhaust system. By contrast, exhaust gas is removed from the housing interior 3 according to an arrow 7 via the exhaust gas outlet 5 during the operation of the exhaust system or during the operation of the internal combustion engine. The exhaust gas inlet 4 and the exhaust gas outlet 5 are fluidically connected with one another for this in the housing interior 3.

(7) The muffler 1 is designed as an end muffler in the example according to FIGS. 1 and 2. An exhaust pipe connected to the exhaust gas outlet 5 is designed in this case as a tail pipe 8, from which the exhaust gas is discharged into the environment 9 during the operation of the exhaust system or the internal combustion engine. In the example shown, the muffler 1 is installed transversely in a vehicle, of which only a rear-side molding 10, which may also be designated the rear apron 10, can be seen in FIGS. 1 and 2. In case of a transversely installed muffler 1, a central longitudinal axis 11 of the muffler 1 extends transversely, i.e., essentially at right angles to a longitudinal direction 12 of the vehicle, which is indicated by a double arrow in FIGS. 1 and 2. Further, the central longitudinal axis 11 of the muffler 1 extends, as a rule, more or less horizontally.

(8) In the installation situation shown in FIGS. 1 and 2, the muffler 1 is arranged relatively close to the rear molding 10, and there is a relatively short distance between the housing 2 and the rear molding 10 especially in an area 13. As a result, the rear molding 10 is subject to thermal load due to the heat emitted from the housing 2 during the operation of the exhaust system, i.e., during the operation of the internal combustion engine.

(9) At its axial ends, the housing 2 has an end panel 14, 15 each, which axially limit the housing interior 3. The housing 2 has, in addition, a jacket 16, which is arranged extending circumferentially in the circumferential direction 17 of the housing 2. The circumferential direction 17 is indicated by a double arrow in FIG. 2. The jacket 16 forms a radial limitation of the housing interior 3.

(10) As can be seen especially in FIG. 1, at least one chamber 18, through which exhaust gas flows during the operation of the exhaust system, which is indicated by a flow arrow 19, is formed in the housing interior 3. This chamber 18 is axially limited at its axial ends by an intermediate panel 20, 21 each. The two intermediate panels 20, 21 are provided in the example in addition to the end panels 14, 15. Further, the two intermediate panels 20, 21 are located at axially spaced locations from the two end panels 14, 15. An additional chamber 22, which will hereinafter be called an absorption chamber 22, is formed hereby in the housing interior 3 between one end panel, which is arranged at the bottom in FIG. 1, and the adjacent intermediate panel 21. An additional chamber 23, which will hereinafter be called resonance chamber 23, is likewise formed between the other end panel 15, which is arranged at the top in FIG. 1, and the intermediate panel 20 located adjacent to it. The absorption chamber 22 may be optionally filled with an absorption material 24, which has an airborne sound-absorbing effect. A discharge line 25, which has an open inlet end 26 arranged in the chamber 18, is passed through the absorption chamber 22 without interruption. On the outlet side, the discharge line 25 leads to the exhaust gas outlet 5, via which it is fluidically connected with the tail pipe 8. Within the absorption chamber 22, the discharge line 25 has a perforation 27, through which the airborne sound can exit into the absorption chamber 22. The exhaust gas does not flow through the absorption chamber 22 here.

(11) The resonance chamber 23 is connected fluidically to the chamber 18 via a connection pipe 28. Since the resonance chamber 23 is otherwise closed, the exhaust gas likewise does not flow through it during the operation of the exhaust system. The connection line 28 and the resonance chamber 23 form a Helmholtz resonator. The chamber 18 itself, through which exhaust gas can flow, acts as a reflection or expansion chamber, which likewise has a muffling effect.

(12) In addition, the muffler 1 has, in the interior 3 of its housing, at least one insulating shell 29, which is arranged in the area of the chamber 18, through which flow can take place, and extends in the circumferential direction 17 along the jacket 16. The two intermediate panels 20, 21, which axially limit said chamber 18, are supported radially on the insulating shell 29 with a radially outer panel edge 30 and 31, respectively. The respective panel support area of the insulating shell 29 is indicated by a curly bracket each and is designated by 32 in FIG. 1. The insulating shell 29 itself is supported radially with its outer shell edge 33 on the jacket 16. Corresponding jacket support areas are indicated by a curly bracket each and designated by 34 in FIG. 1. Furthermore, the insulating shell 29 is shaped or arranged such that an insulating gap 35 is formed radially between the jacket 16 and the insulating shell 29. The insulating gap 35 is limited by a shell edge 33 at least in the axial direction 36 of the housing 2. The axial direction 36 extends parallel to the central longitudinal axis 11 and is indicated by a double arrow in FIG. 1.

(13) As can be seen in FIG. 1, the shell edge 33 is located at an axially spaced location from the intermediate panels 20, 21 and thus at an axially spaced location from the panel support areas 32 at least in the area of the circumferential sections 41, so that the jacket support areas 34 are also located at axially spaced locations from the panel support areas 32.

(14) The insulating shell 29 is smaller than the jacket 16. The insulating shell 29 is shorter in the axial direction 36 than the jacket 16. The insulating shell 29 is located at an axially spaced location from the two end panels 14, 15 in the example. Furthermore, the insulating shell 29 also has smaller dimensions in the circumferential direction 17 than the jacket 16 in the preferred example shown, so that the insulating shell 29 does not extend over the entire circumference of the housing 2, but it extends over less than 360. As can be seen in FIG. 2, the insulating shell 29 extends, for example, over less than 120 in the circumferential direction 17. As a result, the two intermediate panels 20, 21 can be supported radially with their respective panel edges 30, 31 on the insulating shell 29 in a shell section 35 assigned to the insulating shell 29 and can be radially supported directly on the jacket 16 in a jacket section 36. Thus, the respective panel edge 30, 31 is formed by the shell section 35 and the jacket section 36 in the respective intermediate panel 20, 21.

(15) In the area of a transition 37 between the shell section 35 and the jacket section 36, the respective intermediate panel 20, 21 may have a step 38. The shell edge 33 can then be passed axially through the respective intermediate panel 20, 21 in the area of this step 38. Such a step 38 is indicated by means of a broken line at the lower intermediate panel 21 in FIG. 1. The step 38 can be seen in FIGS. 2 and 3. The transition 37, which can be seen in FIG. 2 on the left and at the bottom, is shown in an enlarged view in FIG. 3. Since the shell edge 33 can pass through the respective intermediate panel 20, 21 in the area of the step 38 in this mode of construction, it is possible to support the shell edge 33 circumferentially on the jacket 16 in a closed form. This results in a closed, circumferential contact, which is indicated by a broken line in FIG. 1 and is designated by 39.

(16) An alternative embodiment of the transition 37 is indicated in FIG. 1 with a broken line at the upper intermediate panel 20. The shell edge 33 has an interruption 40 in the area of the intermediate panel 20 in this case. The intermediate panel 20 with its jacket section 36 may extend in this interruption 40 up to the jacket 16, so that the intermediate panel 20 will also be supported now radially on the jacket 16 in the area of the shell edge 33. It is clear that a mixed mode of construction may also be embodied, in principle, so that either the two transitions 37 have different shapes in the same intermediate panel 20, 21, or else the transitions 37 have different shapes in the two intermediate panels 20, 21.

(17) If the insulating shell 29 extends over less than 360 in the circumferential direction 17, it is useful to likewise limit the insulating gap 35 in the circumferential direction 17 by a correspondingly shaped shell edge 33. The shell edge 33 according to FIG. 1 has two circumferential sections 41 extending in the circumferential direction 17 and two axially extending axial sections 42 for this purpose. The two axial sections 42 advantageously connect the two circumferential sections 41, so that the shell edge 33 extends in a closed form on the insulating shell 29. Only one such axial section 42 can be seen in FIG. 1. By contrast, two axial sections 42 can be seen in FIG. 2.

(18) As can be seen especially in FIG. 3, the shell edge 33 has a profile in the cross section, which is shaped such that the contact 39 between the shell edge 33 and the jacket 16 is punctiform in profile, while it is linear along the shell edge 33 according to FIG. 1.

(19) According to FIG. 1, the chamber 18, through which flow is possible, is designed, as was mentioned, as a reflection and/or expansion chamber. A feed line 43, through which exhaust gas enters the chamber 18 during the operation of the exhaust system and which has an open outlet end 44, is provided in this case. In addition, the discharge line 25 is provided, through which exhaust gas leaves the chamber 18 during the operation of the exhaust system and which has the open inlet end 26. The feed line 43 is formed by the exhaust gas inlet 4 in the example, so that the exhaust gas inlet 4 opens here into the chamber 18. Further, the exhaust gas inlet 4 opens here into the chamber 18 through the jacket 16. Further, provisions are made for the exhaust gas inlet 4 to open into the chamber 18 on an opposite side of the jacket 16 in relation to the insulating shell 29. The exhaust gas inlet 4 is preferably aligned with the chamber 18 such that an inflow direction 45 is obtained with which the exhaust gas flows into the chamber 18 during the operation of the exhaust system and which reaches the insulating shell 29. The orientation of the exhaust gas inlet 4 aligned with the insulating shell 29 is indicated in FIG. 2, in addition, by a dash-dotted line 46, which forms an extension of the direction arrow of the inflow direction 45 and which reaches the insulating shell 29.

(20) FIG. 2 shows, in addition, that the exhaust gas inlet 4 is connected to the jacket 16 in the circumferential direction 17 outside the insulating shell 29. In respect to the intermediate panels 20, 21, this means that the exhaust gas inlet 4 is connected to the jacket 16 in the area of the jacket sections 36.

(21) As can be seen in FIGS. 2 and 3, an insulating material 47 may be arranged in the insulating gap 35. The insulating material 47 may be formed in the form of a mat consisting of a suitable, heat-insulating material. The insulating material 47 has a heat-insulating effect and thus reduces the heat transfer between the insulating shell 29 and the jacket 16.

(22) The insulating material 47 is advantageously fixed on the insulating shell 29. According to FIGS. 3 and 4, provisions may be made for fixing the insulating material 47 within the insulating gap 35, for fixing sections 48, which mesh with the insulating material 47, to be bent out on the insulating shell 29. Further, these fixing sections 48 are dimensioned such that they do not touch the jacket 16. Due to the bent-out fixing sections 48, the insulating shell 29 contains recesses 49, which are complementary thereto and are formed by bending out the fixing sections 48. The fixing sections 48 are provided with a triangular geometry in the example. To prepare the fixing sections 48, two sides of these triangles are cut free and the particular fixing section cut free is then bent over around the third side. The fixing section 48 mesh with the insulating material 47 in a thorn-like manner, as a result of which this insulating material is fixed sufficiently in its position.

(23) As can be seen in FIG. 1, the end panels 14, 15 advantageously also have a circumferential panel edge 50, via which the end panels 14, 15 are radially supported on the jacket 16. Unlike in the intermediate panels 20, 21, the panel edges 50 are supported, however, in case of the end panels 14, 15 on the jacket 16 in a closed, circumferentially extending form in the circumferential direction 17.

(24) To embody an inexpensive embodiment, the jacket 16 itself has a single-walled design. A locally limited double-walled structure is embodied for the jacket 16 only in the area of the insulating shell 29 in connection with the insulating shell 29.

(25) The insulating shell 29 is advantageously manufactured from a steel plate, preferably a stainless steel plate.

(26) For a simplified assembly, at least the insulating shell 29 and the two intermediate panels 20, 21 may be integrated into a muffler insert or functional insert. The intermediate panels 20, 21 may be welded for this purpose to the insulating shell 29 along the respective shell section 30, 31. After inserting this muffler insert into the jacket 16, which may be performed, in principle, axially, the intermediate panels 20, 21 can be welded to the jacket 16 along their jacket sections 36. A welded connection may likewise be provided between the shell edge 33 and the jacket 16. Said welded connections may be formed by weld seams or by welding spots.

(27) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.